changeset 1072:6468a5f6ec79 feature/grids/LaplaceSquared

Merge with default
author Jonatan Werpers <jonatan@werpers.com>
date Tue, 12 Feb 2019 17:12:42 +0100
parents 92cb03e64ca4 (current diff) c7b619cf5e34 (diff)
children 95113a592421
files +sbp/+implementations/intOpAWW_orders_2to2_ratio2to1.m +sbp/+implementations/intOpAWW_orders_2to2_ratio_2to1_accC2F1_accF2C2.m +sbp/+implementations/intOpAWW_orders_2to2_ratio_2to1_accC2F2_accF2C1.m +sbp/+implementations/intOpAWW_orders_4to4_ratio2to1.m +sbp/+implementations/intOpAWW_orders_4to4_ratio_2to1_accC2F2_accF2C3.m +sbp/+implementations/intOpAWW_orders_4to4_ratio_2to1_accC2F3_accF2C2.m +sbp/+implementations/intOpAWW_orders_6to6_ratio2to1.m +sbp/+implementations/intOpAWW_orders_6to6_ratio_2to1_accC2F3_accF2C4.m +sbp/+implementations/intOpAWW_orders_6to6_ratio_2to1_accC2F4_accF2C3.m +sbp/+implementations/intOpAWW_orders_8to8_ratio2to1.m +sbp/+implementations/intOpAWW_orders_8to8_ratio_2to1_accC2F4_accF2C5.m +sbp/+implementations/intOpAWW_orders_8to8_ratio_2to1_accC2F5_accF2C4.m +sbp/InterpAWW.m +sbp/InterpMC.m +scheme/Beam2d.m +scheme/TODO.txt +scheme/Wave.m +scheme/Wave2dCurve.m +scheme/error1d.m +scheme/error2d.m +scheme/errorMax.m +scheme/errorRelative.m +scheme/errorSbp.m +scheme/errorVector.m +time/+cdiff/cdiff.m
diffstat 82 files changed, 3209 insertions(+), 2284 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+grid/Nodes.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,47 @@
+classdef Nodes < grid.Grid
+    properties
+        coords
+    end
+
+    methods
+        % Creates a grid with one point for each row in coords.
+        % The dimension equals the number of columns in coords.
+        function obj = Nodes(coords)
+            obj.coords = coords;
+        end
+
+        function o = N(obj)
+            o = size(obj.coords, 1);
+        end
+
+        % d returns the spatial dimension of the grid
+        function o = D(obj)
+            o = size(obj.coords, 2);
+        end
+
+        % points returns a n x d matrix containing the coordinates for all points.
+        function X = points(obj)
+            X = obj.coords;
+        end
+
+        % Restricts the grid function gf on obj to the subgrid g.
+        function gf = restrictFunc(obj, gf, g)
+            error('Not implemented');
+        end
+
+        % Projects the grid function gf on obj to the grid g.
+        function gf = projectFunc(obj, gf, g)
+            error('Not implemented');
+        end
+
+        % Return the grid.boundaryIdentifiers of all boundaries in a cell array.
+        function bs = getBoundaryNames(obj)
+            error('Not implemented');
+        end
+
+        % Return coordinates for the given boundary
+        function b = getBoundary(obj, name)
+            error('Not implemented');
+        end
+    end
+end
--- a/+multiblock/+domain/Circle.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+multiblock/+domain/Circle.m	Tue Feb 12 17:12:42 2019 +0100
@@ -65,10 +65,10 @@
             conn{5,2} = {'n','s'};
 
             boundaryGroups = struct();
-            boundaryGroups.E = multiblock.BoundaryGroup({2,'e'});
-            boundaryGroups.N = multiblock.BoundaryGroup({3,'n'});
-            boundaryGroups.W = multiblock.BoundaryGroup({4,'n'});
-            boundaryGroups.S = multiblock.BoundaryGroup({5,'e'});
+            boundaryGroups.E = multiblock.BoundaryGroup({{2,'e'}});
+            boundaryGroups.N = multiblock.BoundaryGroup({{3,'n'}});
+            boundaryGroups.W = multiblock.BoundaryGroup({{4,'n'}});
+            boundaryGroups.S = multiblock.BoundaryGroup({{5,'e'}});
             boundaryGroups.all = multiblock.BoundaryGroup({{2,'e'},{3,'n'},{4,'n'},{5,'e'}});
 
             obj = obj@multiblock.DefCurvilinear(blocks, conn, boundaryGroups, blocksNames);
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+multiblock/+domain/Line.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,153 @@
+classdef Line < multiblock.Definition
+    properties
+
+    xlims
+    blockNames % Cell array of block labels
+    nBlocks
+    connections % Cell array specifying connections between blocks
+    boundaryGroups % Structure of boundaryGroups
+
+    end
+
+
+    methods
+        % Creates a divided line
+        % x is a vector of boundary and interface positions.
+        % blockNames: cell array of labels. The id is default.
+        function obj = Line(x,blockNames)
+            default_arg('blockNames',[]);
+
+            N = length(x)-1; % number of blocks in the x direction.
+
+            if ~issorted(x)
+                error('The elements of x seem to be in the wrong order');
+            end
+
+            % Dimensions of blocks and number of points
+            blockTi = cell(N,1);
+            xlims = cell(N,1);
+            for i = 1:N
+                xlims{i} = {x(i), x(i+1)};
+            end
+
+            % Interface couplings
+            conn = cell(N,N);
+            for i = 1:N
+                conn{i,i+1} = {'r','l'};
+            end
+
+            % Block names (id number as default)
+            if isempty(blockNames)
+                obj.blockNames = cell(1, N);
+                for i = 1:N
+                    obj.blockNames{i} = sprintf('%d', i);
+                end
+            else
+                assert(length(blockNames) == N);
+                obj.blockNames = blockNames;
+            end
+            nBlocks = N;
+
+            % Boundary groups
+            boundaryGroups = struct();
+            L = { {1, 'l'} };
+            R = { {N, 'r'} };
+            boundaryGroups.L = multiblock.BoundaryGroup(L);
+            boundaryGroups.R = multiblock.BoundaryGroup(R);
+            boundaryGroups.all = multiblock.BoundaryGroup([L,R]);
+
+            obj.connections = conn;
+            obj.nBlocks = nBlocks;
+            obj.boundaryGroups = boundaryGroups;
+            obj.xlims = xlims;
+
+        end
+
+
+        % Returns a multiblock.Grid given some parameters
+        % ms: cell array of m values 
+        % For same m in every block, just input one scalar.
+        function g = getGrid(obj, ms, varargin)
+
+            default_arg('ms',21)
+
+            % Extend ms if input is a single scalar
+            if (numel(ms) == 1) && ~iscell(ms)
+                m = ms;
+                ms = cell(1,obj.nBlocks);
+                for i = 1:obj.nBlocks
+                    ms{i} = m;
+                end
+            end
+
+            grids = cell(1, obj.nBlocks);
+            for i = 1:obj.nBlocks
+                grids{i} = grid.equidistant(ms{i}, obj.xlims{i}, obj.ylims{i});
+            end
+
+            g = multiblock.Grid(grids, obj.connections, obj.boundaryGroups);
+        end
+
+        % Returns a multiblock.Grid given some parameters
+        % ms: cell array of m values 
+        % For same m in every block, just input one scalar.
+        function g = getStaggeredGrid(obj, ms, varargin)
+
+            default_arg('ms',21)
+
+            % Extend ms if input is a single scalar
+            if (numel(ms) == 1) && ~iscell(ms)
+                m = ms;
+                ms = cell(1,obj.nBlocks);
+                for i = 1:obj.nBlocks
+                    ms{i} = m;
+                end
+            end
+
+            grids = cell(1, obj.nBlocks);
+            for i = 1:obj.nBlocks
+                [g_primal, g_dual] = grid.primalDual1D(ms{i}, obj.xlims{i});
+                grids{i} = grid.Staggered1d(g_primal, g_dual);
+            end
+
+            g = multiblock.Grid(grids, obj.connections, obj.boundaryGroups);
+        end
+
+        % label is the type of label used for plotting,
+        % default is block name, 'id' show the index for each block.
+        function show(obj, label)
+            default_arg('label', 'name')
+
+            m = 10;
+            figure
+            for i = 1:obj.nBlocks
+               x = linspace(obj.xlims{i}{1}, obj.xlims{i}{2}, m);
+               y = 0*x + 0.05* ( (-1)^i + 1 ) ;
+               plot(x,y,'+');
+               hold on 
+            end
+            hold off
+
+            switch label
+                case 'name'
+                    labels = obj.blockNames;
+                case 'id'
+                    labels = {};
+                    for i = 1:obj.nBlocks
+                        labels{i} = num2str(i);
+                    end
+                otherwise
+                    axis equal
+                    return
+            end
+
+            legend(labels)
+            axis equal
+        end
+
+        % Returns the grid size of each block in a cell array
+        % The input parameters are determined by the subclass
+        function ms = getGridSizes(obj, varargin)
+        end
+    end
+end
--- a/+multiblock/DiffOp.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+multiblock/DiffOp.m	Tue Feb 12 17:12:42 2019 +0100
@@ -10,7 +10,7 @@
     end
 
     methods
-        function obj = DiffOp(doHand, g, order, doParam)
+        function obj = DiffOp(doHand, g, order, doParam, intfTypes)
             %  doHand -- may either be a function handle or a cell array of
             %            function handles for each grid. The function handle(s)
             %            should be on the form do = doHand(grid, order, ...)
@@ -24,14 +24,17 @@
             %            corresponding function handle as extra parameters:
             %            doHand(..., doParam{i}{:}) Otherwise doParam is sent as
             %            extra parameters to all doHand: doHand(..., doParam{:})
+            %
+            % intfTypes (optional) -- nBlocks x nBlocks cell array of types for
+            %                                 every interface.
             default_arg('doParam', [])
+            default_arg('intfTypes', cell(g.nBlocks(), g.nBlocks()) );
 
             [getHand, getParam] = parseInput(doHand, g, doParam);
 
+            obj.order = order;
             nBlocks = g.nBlocks();
 
-            obj.order = order;
-
             % Create the diffOps for each block
             obj.diffOps = cell(1, nBlocks);
             for i = 1:nBlocks
@@ -70,12 +73,11 @@
                         continue
                     end
 
-
-                    [ii, ij] = obj.diffOps{i}.interface(intf{1}, obj.diffOps{j}, intf{2});
+                    [ii, ij] = obj.diffOps{i}.interface(intf{1}, obj.diffOps{j}, intf{2}, intfTypes{i,j});
                     D{i,i} = D{i,i} + ii;
                     D{i,j} = D{i,j} + ij;
 
-                    [jj, ji] = obj.diffOps{j}.interface(intf{2}, obj.diffOps{i}, intf{1});
+                    [jj, ji] = obj.diffOps{j}.interface(intf{2}, obj.diffOps{i}, intf{1}, intfTypes{i,j});
                     D{j,j} = D{j,j} + jj;
                     D{j,i} = D{j,i} + ji;
                 end
@@ -127,11 +129,11 @@
 
         % Get a boundary operator specified by opName for the given boundary/BoundaryGroup
         function op = getBoundaryOperator(obj, opName, boundary)
+
             switch class(boundary)
                 case 'cell'
-                    localOpName = [opName '_' boundary{2}];
                     blockId = boundary{1};
-                    localOp = obj.diffOps{blockId}.(localOpName);
+                    localOp = obj.diffOps{blockId}.getBoundaryOperator(opName, boundary{2});
 
                     div = {obj.blockmatrixDiv{1}, size(localOp,2)};
                     blockOp = blockmatrix.zero(div);
@@ -149,13 +151,10 @@
         end
 
         function op = getBoundaryQuadrature(obj, boundary)
-            opName = 'H';
             switch class(boundary)
                 case 'cell'
-                    localOpName = [opName '_' boundary{2}];
                     blockId = boundary{1};
-                    op = obj.diffOps{blockId}.(localOpName);
-
+                    op = obj.diffOps{blockId}.getBoundaryQuadrature(boundary{2});
                     return
                 case 'multiblock.BoundaryGroup'
                     N = length(boundary);
@@ -201,33 +200,8 @@
             [blockClosure, blockPenalty] = obj.diffOps{I}.boundary_condition(name, type);
 
             % Expand to matrix for full domain.
-            div = obj.blockmatrixDiv;
-            if ~iscell(blockClosure)
-                temp = blockmatrix.zero(div);
-                temp{I,I} = blockClosure;
-                closure = blockmatrix.toMatrix(temp);
-            else
-                for i = 1:length(blockClosure)
-                    temp = blockmatrix.zero(div);
-                    temp{I,I} = blockClosure{i};
-                    closure{i} = blockmatrix.toMatrix(temp);
-                end
-            end
-
-            if ~iscell(blockPenalty)
-                div{2} = size(blockPenalty, 2); % Penalty is a column vector
-                p = blockmatrix.zero(div);
-                p{I} = blockPenalty;
-                penalty = blockmatrix.toMatrix(p);
-            else
-                % TODO: used by beam equation, should be eliminated. SHould only set one BC per call
-                for i = 1:length(blockPenalty)
-                    div{2} = size(blockPenalty{i}, 2); % Penalty is a column vector
-                    p = blockmatrix.zero(div);
-                    p{I} = blockPenalty{i};
-                    penalty{i} = blockmatrix.toMatrix(p);
-                end
-            end
+            closure = multiblock.local2globalClosure(blockClosure, obj.blockmatrixDiv, I);
+            penalty = multiblock.local2globalPenalty(blockPenalty, obj.blockmatrixDiv, I);
         end
 
         function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+multiblock/local2globalClosure.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,10 @@
+% Takes the block-local closures and turns it into a global closure
+%   local -- The local closure
+%   div   -- block matrix division for the diffOp
+%   I     -- Index of blockmatrix block
+function closure = local2globalClosure(local, div, I)
+    closure_bm = blockmatrix.zero(div);
+    closure_bm{I,I} = local;
+
+    closure = blockmatrix.toMatrix(closure_bm);
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+multiblock/local2globalPenalty.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,11 @@
+% Takes the block-local penalty and turns it into a global penalty
+%   local -- The local penalty
+%   div   -- block matrix division for the diffOp
+%   I     -- Index of blockmatrix block
+function penalty = local2globalPenalty(local, div, I)
+    penaltyDiv = {div{1}, size(local,2)};
+    penalty_bm = blockmatrix.zero(penaltyDiv);
+    penalty_bm{I,1} = local;
+
+    penalty = blockmatrix.toMatrix(penalty_bm);
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+multiblock/setAllInterfaceTypes.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,13 @@
+% Create interface configuration with a single type for all interfaces
+%    g -- multiblock grid
+% type -- type for all interfaces
+function intfTypes = setAllInterfaceTypes(g, type)
+	intfTypes = cell(g.nBlocks(), g.nBlocks());
+	for i = 1:g.nBlocks()
+		for j = 1:g.nBlocks()
+			if ~isempty(g.connections{i,j})
+				intfTypes{i,j} = type;
+			end
+		end
+	end
+end
--- a/+sbp/+implementations/intOpAWW_orders_2to2_ratio2to1.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,47 +0,0 @@
-function [IC2F,IF2C,Hc,Hf] = IntOp_orders_2to2_ratio2to1(mc,hc,ACC)
-
-% ACC is a string.
-% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
-% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
-ratio = 2;
-mf = ratio*mc-1; 
-hf = hc/ratio;
-
-switch ACC
-    case 'F2C'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_2to2_ratio_2to1_accC2F1_accF2C2;
-    case 'C2F'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_2to2_ratio_2to1_accC2F2_accF2C1;
-end
-
-stencil_width = length(stencil_F2C);
-stencil_hw = (stencil_width-1)/2;
-[BC_rows,BC_cols] = size(BC_F2C);
-
-%%% Norm matrices %%%
-Hc = speye(mc,mc);
-HcUm = length(HcU); 
-Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
-Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
-Hc = Hc*hc;
-
-Hf = speye(mf,mf);
-HfUm = length(HfU);
-Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
-Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
-Hf = Hf*hf;
-%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IF2C from stencil and BC
-IF2C = sparse(mc,mf);
-for i = BC_rows+1 : mc-BC_rows
-    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
-end
-IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
-IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IC2F using symmetry condition %%%%
-IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- a/+sbp/+implementations/intOpAWW_orders_2to2_ratio_2to1_accC2F1_accF2C2.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,17 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_2to2_ratio_2to1_accC2F1_accF2C2
-%INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F1_ACCF2C2_STENCIL_5_BC_2_5
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F1_ACCF2C2_STENCIL_5_BC_2_5
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:36:07
-
-stencil_F2C = [-1.0./8.0,1.0./4.0,3.0./4.0,1.0./4.0,-1.0./8.0];
-if nargout > 1
-    BC_F2C = reshape([6.288191560529559e-1,-6.440957802647795e-2,6.855471317807184e-1,1.572264341096408e-1,-2.438028498638558e-1,7.469014249319279e-1,-8.431231982626708e-2,2.921561599131335e-1,1.374888185644862e-2,-1.318744409282243e-1],[2,5]);
-end
-if nargout > 2
-    HcU = 1.0./2.0;
-end
-if nargout > 3
-    HfU = 1.0./2.0;
-end
--- a/+sbp/+implementations/intOpAWW_orders_2to2_ratio_2to1_accC2F2_accF2C1.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,17 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_2to2_ratio_2to1_accC2F2_accF2C1
-%INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F2_ACCF2C1_STENCIL_5_BC_1_3
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F2_ACCF2C1_STENCIL_5_BC_1_3
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:36:08
-
-stencil_F2C = [1.0./4.0,1.0./2.0,1.0./4.0];
-if nargout > 1
-    BC_F2C = [1.0./2.0,1.0./2.0];
-end
-if nargout > 2
-    HcU = 1.0./2.0;
-end
-if nargout > 3
-    HfU = 1.0./2.0;
-end
--- a/+sbp/+implementations/intOpAWW_orders_4to4_ratio2to1.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,47 +0,0 @@
-function [IC2F,IF2C,Hc,Hf] = IntOp_orders_4to4_ratio2to1(mc,hc,ACC)
-
-% ACC is a string.
-% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
-% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
-ratio = 2;
-mf = ratio*mc-1; 
-hf = hc/ratio;
-
-switch ACC
-    case 'F2C'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_4to4_ratio_2to1_accC2F2_accF2C3;
-    case 'C2F'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_4to4_ratio_2to1_accC2F3_accF2C2;
-end
-
-stencil_width = length(stencil_F2C);
-stencil_hw = (stencil_width-1)/2;
-[BC_rows,BC_cols] = size(BC_F2C);
-
-%%% Norm matrices %%%
-Hc = speye(mc,mc);
-HcUm = length(HcU); 
-Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
-Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
-Hc = Hc*hc;
-
-Hf = speye(mf,mf);
-HfUm = length(HfU);
-Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
-Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
-Hf = Hf*hf;
-%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IF2C from stencil and BC
-IF2C = sparse(mc,mf);
-for i = BC_rows+1 : mc-BC_rows
-    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
-end
-IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
-IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IC2F using symmetry condition %%%%
-IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- a/+sbp/+implementations/intOpAWW_orders_4to4_ratio_2to1_accC2F2_accF2C3.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,18 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_4to4_ratio_2to1_accC2F2_accF2C3
-%INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F2_ACCF2C3_STENCIL_9_BC_3_11
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F2_ACCF2C3_STENCIL_9_BC_3_11
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:36:01
-
-stencil_F2C = [7.0./2.56e2,-1.0./3.2e1,-7.0./6.4e1,9.0./3.2e1,8.5e1./1.28e2,9.0./3.2e1,-7.0./6.4e1,-1.0./3.2e1,7.0./2.56e2];
-if nargout > 1
-    BC_F2C = reshape([7.523257802630956e-2,2.447812262221267e-1,-1.679313063616916e-1,1.290510950666589,6.315723344677289e-3,1.67178747937954e-1,1.982667903557025,-7.554383893379468e-1,7.215271362899867e-1,-2.820478831383137,1.807034411305536,-7.589683751979843e-1,-7.685973268458095e-1,3.965751544535173e-1,4.119789638051451e-1,1.574000556785898e-1,-1.113618964927466e-1,3.631000220124657e-1,1.639694219982991,-9.114074742274862e-1,4.952715520862987e-1,-4.524162151353456e-1,2.65481378213589e-1,-2.268273408674622e-1,3.455365956773523e-1,-2.009765975089827e-1,1.722179564305811e-1,-5.52933488235368e-1,3.18109976271229e-1,-2.171481232558432e-1,1.033835580108027e-1,-5.911351224351343e-2,3.960076712054991e-2],[3,11]);
-end
-if nargout > 2
-    t2 = [1.7e1./4.8e1,5.9e1./4.8e1,4.3e1./4.8e1,4.9e1./4.8e1];
-    HcU = t2;
-end
-if nargout > 3
-    HfU = t2;
-end
--- a/+sbp/+implementations/intOpAWW_orders_4to4_ratio_2to1_accC2F3_accF2C2.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,18 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_4to4_ratio_2to1_accC2F3_accF2C2
-%INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F3_ACCF2C2_STENCIL_9_BC_3_11
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F3_ACCF2C2_STENCIL_9_BC_3_11
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:36:05
-
-stencil_F2C = [-1.0./2.56e2,-1.0./3.2e1,1.0./6.4e1,9.0./3.2e1,6.1e1./1.28e2,9.0./3.2e1,1.0./6.4e1,-1.0./3.2e1,-1.0./2.56e2];
-if nargout > 1
-    BC_F2C = reshape([1.0./2.0,0.0,0.0,1.77e2./2.72e2,3.0./8.0,-5.9e1./6.88e2,1.125919117647059e-2,3.546742584745763e-1,1.335392441860465e-2,-4.9e1./5.44e2,2.335805084745763e-1,3.204941860465116e-1,-1.194852941176471e-2,1.350635593220339e-2,5.308866279069767e-1,-9.0./5.44e2,-1.11228813559322e-2,2.943313953488372e-1,-2.803308823529412e-2,2.105402542372881e-2,-1.580668604651163e-2,-9.0./5.44e2,1.430084745762712e-2,-5.450581395348837e-2,-9.191176470588235e-4,7.944915254237288e-4,-5.450581395348837e-3,1.0./5.44e2,-1.588983050847458e-3,2.180232558139535e-3,2.297794117647059e-4,-1.986228813559322e-4,2.725290697674419e-4],[3,11]);
-end
-if nargout > 2
-    t2 = [1.7e1./4.8e1,5.9e1./4.8e1,4.3e1./4.8e1,4.9e1./4.8e1];
-    HcU = t2;
-end
-if nargout > 3
-    HfU = t2;
-end
--- a/+sbp/+implementations/intOpAWW_orders_6to6_ratio2to1.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,47 +0,0 @@
-function [IC2F,IF2C,Hc,Hf] = IntOp_orders_6to6_ratio2to1(mc,hc,ACC)
-
-% ACC is a string.
-% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
-% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
-ratio = 2;
-mf = ratio*mc-1; 
-hf = hc/ratio;
-
-switch ACC
-    case 'F2C'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_6to6_ratio_2to1_accC2F3_accF2C4;
-    case 'C2F'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_6to6_ratio_2to1_accC2F4_accF2C3;
-end
-
-stencil_width = length(stencil_F2C);
-stencil_hw = (stencil_width-1)/2;
-[BC_rows,BC_cols] = size(BC_F2C);
-
-%%% Norm matrices %%%
-Hc = speye(mc,mc);
-HcUm = length(HcU); 
-Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
-Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
-Hc = Hc*hc;
-
-Hf = speye(mf,mf);
-HfUm = length(HfU);
-Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
-Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
-Hf = Hf*hf;
-%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IF2C from stencil and BC
-IF2C = sparse(mc,mf);
-for i = BC_rows+1 : mc-BC_rows
-    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
-end
-IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
-IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IC2F using symmetry condition %%%%
-IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- a/+sbp/+implementations/intOpAWW_orders_6to6_ratio_2to1_accC2F3_accF2C4.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,18 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_6to6_ratio_2to1_accC2F3_accF2C4
-%INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F3_ACCF2C4_STENCIL_13_BC_3_17
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F3_ACCF2C4_STENCIL_13_BC_3_17
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:35:47
-
-stencil_F2C = [-5.95703125e-3,3.0./5.12e2,3.57421875e-2,-2.5e1./5.12e2,-8.935546875e-2,7.5e1./2.56e2,3.17e2./5.12e2,7.5e1./2.56e2,-8.935546875e-2,-2.5e1./5.12e2,3.57421875e-2,3.0./5.12e2,-5.95703125e-3];
-if nargout > 1
-    BC_F2C = reshape([5.233890618131365e-1,-1.594459192645467e-2,3.532688727637403e-2,8.021234957689208e-1,3.90683205173562e-1,-1.73222951632239e-1,-8.87662686483442e-2,2.90091235796637e-1,-1.600356115709148e-1,-1.044025375027475e-1,2.346179009198368e-1,6.091329306528956e-1,1.561275522703128e-1,-1.168382445709856e-1,1.040987887887311,-2.387061036980731e-1,1.363504965974361e-1,1.082611928255256e-1,-5.745310654054326e-1,3.977694249198785e-1,-9.376217911402619e-1,3.554518646054656e-2,5.609157787396987e-5,-1.564625311232018e-1,6.107907974027401e-1,-3.786608696698368e-1,7.02265869951125e-1,2.054294270642538e-1,-1.302300112378257e-1,2.478941407690889e-1,-2.657085326191479e-1,1.568761445933572e-1,-2.632906518005349e-1,-1.228047556139644e-1,7.182193248980271e-2,-1.1291238242346e-1,5.811258780405158e-2,-3.466364400805378e-2,5.683680203338252e-2,1.781337575097077e-2,-1.030572999042704e-2,1.577197067502767e-2,-1.443802115768554e-2,8.391316308374261e-3,-1.29534117369052e-2,-1.548018627738296e-3,8.794183904936319e-4,-1.298961407229805e-3,1.573818938200601e-3,-8.940753636685258e-4,1.320610764016968e-3],[3,17]);
-end
-if nargout > 2
-    t2 = [3.159490740740741e-1,1.390393518518519,6.275462962962963e-1,1.240509259259259,9.116898148148148e-1,1.013912037037037];
-    HcU = t2;
-end
-if nargout > 3
-    HfU = t2;
-end
--- a/+sbp/+implementations/intOpAWW_orders_6to6_ratio_2to1_accC2F4_accF2C3.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,18 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_6to6_ratio_2to1_accC2F4_accF2C3
-%INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F4_ACCF2C3_STENCIL_13_BC_4_17
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F4_ACCF2C3_STENCIL_13_BC_4_17
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:35:56
-
-stencil_F2C = [1.07421875e-3,3.0./5.12e2,-6.4453125e-3,-2.5e1./5.12e2,1.611328125e-2,7.5e1./2.56e2,2.45e2./5.12e2,7.5e1./2.56e2,1.611328125e-2,-2.5e1./5.12e2,-6.4453125e-3,3.0./5.12e2,1.07421875e-3];
-if nargout > 1
-    BC_F2C = reshape([1.0./2.0,0.0,0.0,0.0,6.876076086160158e-1,1.5e1./3.2e1,-3.461879841386942e-1,3.502577439820862e-2,3.099721991995751e-3,2.228547003766753e-1,9.363652999354482e-3,-3.15791046603844e-3,-1.05789143206462e-1,2.35563165945226e-1,6.070385985337514e-1,-4.847496617839149e-2,-4.809232246867902e-3,5.154694068405061e-3,7.049223649022501e-1,1.016749349808733e-2,3.460117842882262e-2,-4.996621498584866e-2,5.210650763094799e-1,2.233592875303228e-1,-2.239024779745769e-3,4.254668119953384e-4,9.213872590833641e-3,3.910524351558127e-1,-9.048711215107334e-2,8.597375629526346e-2,-3.468219752858724e-1,3.250682992395969e-1,-1.309107466664224e-1,1.199249722306043e-1,-4.071552384959425e-1,1.474417123938701e-1,-3.02863877390285e-2,3.046016554982103e-2,-1.081315128181483e-1,1.120705238850532e-2,7.977722870036266e-2,-6.772545887788229e-2,2.00270418837606e-1,-5.427183680490763e-2,6.524845570188292e-2,-5.637610037043203e-2,1.711235764016968e-1,-4.203646902407166e-2,4.639548341453586e-3,-4.055884445496545e-3,1.258630924935448e-2,-2.776451559292779e-3,-1.023784366070774e-2,8.817108288936985e-3,-2.659664906860937e-2,7.14445034054861e-3,-1.435466025441424e-3,1.240274208149505e-3,-3.764718680837329e-3,1.028716295017727e-3,1.032012418492197e-3,-8.794183904936319e-4,2.597922814459609e-3,-6.571159498040679e-4,1.892022767235695e-4,-1.612267049238325e-4,4.76285849317595e-4,-1.204712574640791e-4],[4,17]);
-end
-if nargout > 2
-    t2 = [3.159490740740741e-1,1.390393518518519,6.275462962962963e-1,1.240509259259259,9.116898148148148e-1,1.013912037037037];
-    HcU = t2;
-end
-if nargout > 3
-    HfU = t2;
-end
--- a/+sbp/+implementations/intOpAWW_orders_8to8_ratio2to1.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,47 +0,0 @@
-function [IC2F,IF2C,Hc,Hf] = IntOp_orders_8to8_ratio2to1(mc,hc,ACC)
-
-% ACC is a string.
-% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
-% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
-ratio = 2;
-mf = ratio*mc-1; 
-hf = hc/ratio;
-
-switch ACC
-    case 'F2C'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_8to8_ratio_2to1_accC2F4_accF2C5;
-    case 'C2F'
-        [stencil_F2C,BC_F2C,HcU,HfU] = ...
-        sbp.implementations.intOpAWW_orders_8to8_ratio_2to1_accC2F5_accF2C4;
-end
-
-stencil_width = length(stencil_F2C);
-stencil_hw = (stencil_width-1)/2;
-[BC_rows,BC_cols] = size(BC_F2C);
-
-%%% Norm matrices %%%
-Hc = speye(mc,mc);
-HcUm = length(HcU); 
-Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
-Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
-Hc = Hc*hc;
-
-Hf = speye(mf,mf);
-HfUm = length(HfU);
-Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
-Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
-Hf = Hf*hf;
-%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IF2C from stencil and BC
-IF2C = sparse(mc,mf);
-for i = BC_rows+1 : mc-BC_rows
-    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
-end
-IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
-IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-%%% Create IC2F using symmetry condition %%%%
-IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- a/+sbp/+implementations/intOpAWW_orders_8to8_ratio_2to1_accC2F4_accF2C5.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,18 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_8to8_ratio_2to1_accC2F4_accF2C5
-%INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F4_ACCF2C5_STENCIL_17_BC_5_24
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F4_ACCF2C5_STENCIL_17_BC_5_24
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:35:02
-
-stencil_F2C = [1.324608212425595e-3,-1.220703125e-3,-1.059686569940476e-2,1.1962890625e-2,3.708902994791667e-2,-5.9814453125e-2,-7.417805989583333e-2,2.99072265625e-1,5.927225748697917e-1,2.99072265625e-1,-7.417805989583333e-2,-5.9814453125e-2,3.708902994791667e-2,1.1962890625e-2,-1.059686569940476e-2,-1.220703125e-3,1.324608212425595e-3];
-if nargout > 1
-    BC_F2C = reshape([2.087365925359584,-1.227221822236823,1.090916714284468e1,-1.041312149906314,1.134214373258162,-1.269686811479259,2.075368250436277,-1.520771409696474e1,1.389750473974189,-1.48485748783569,-1.040579640776707,8.899721508624742e-1,-7.177691661032869,6.882712043721976e-1,-7.599347599660409e-1,-1.26440526850463,1.160658043364166,-5.391509178445742,6.679923135342851e-1,-7.521725463922262e-1,3.752349810676949,-2.906684049793639,2.672876913566556e1,-2.493145660873,2.782825829667436,1.443588084644871e-1,-1.307230271348211e-1,2.216804748506809,1.437719804483573e-1,-1.145830952112369e-1,3.2149320801083e-1,-2.34361439272989e-1,1.855837403850803,1.286992417665136e-1,-5.758238484341108e-2,-1.301103772185027,9.973408313121463e-1,-8.837520107531879,9.534930382604288e-1,-1.429199518808459e-2,-2.384453600787036,1.818345997558567,-1.577342441239303e1,1.422846302346762,3.154159322410927e-3,3.589377915408905e-1,-2.109524979864723e-1,9.363227187483732e-1,6.301238593470628e-2,5.732390257964316e-2,2.793582225299658,-2.033528056927806,1.621324028555783e1,-1.189222718426265,6.189671387692164e-2,5.342131492864642e-1,-4.222231296997605e-1,3.787253511209165,-3.350064226195165e-1,1.245325350855226e-2,-2.184146687275183,1.551331905163865,-1.19387312118926e1,8.349589004472998e-1,-1.35383591594438e-1,-8.014367493869704e-1,5.668415377001197e-1,-4.302842643863972,2.84183319528176e-1,3.83514596570461e-2,9.45794880458861e-1,-6.732638898386457e-1,5.234390273661413,-3.83498639699941e-1,1.440453495443018e-1,5.645065377027613e-1,-4.039220855868618e-1,3.170156487564899,-2.383074337879712e-1,1.216617375214008e-1,-1.937863224145611e-1,1.358891032584724e-1,-1.023378722711107,6.830621267493578e-2,-4.169135139842575e-3,2.270306426219975e-2,-2.38399209865252e-2,2.928388757260058e-1,-4.02060181933195e-2,6.880595419697505e-2,9.638828970166005e-2,-6.98778025332229e-2,5.609317796857676e-1,-4.429526993510467e-2,2.882554468024363e-2,3.582431391759518e-2,-2.671910644265286e-2,2.251335440088556e-1,-1.966486325944329e-2,1.791756577091828e-2,-3.350790201878844e-1,2.581411034605136e-1,-2.283079071439122,2.162064132948073e-1,-2.321676317817421e-1,6.356644993195555e-2,-4.921907141164279e-2,4.384534411523264e-1,-4.198474091936761e-2,4.597203884996652e-2,2.261662512481835e-2,-1.740429407604355e-2,1.537038474929879e-1,-1.452709057733876e-2,1.556101844926456e-2,3.097679325854209e-2,-2.394872918869654e-2,2.128879105995857e-1,-2.032077838507769e-2,2.213372706946953e-2],[5,24]);
-end
-if nargout > 2
-    t2 = [2.948906761778786e-1,1.525720623897707,2.57452876984127e-1,1.798113701499118,4.127080577601411e-1,1.278484623015873,9.232955798059965e-1,1.009333860859158];
-    HcU = t2;
-end
-if nargout > 3
-    HfU = t2;
-end
--- a/+sbp/+implementations/intOpAWW_orders_8to8_ratio_2to1_accC2F5_accF2C4.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,18 +0,0 @@
-function [stencil_F2C,BC_F2C,HcU,HfU] = intOpAWW_orders_8to8_ratio_2to1_accC2F5_accF2C4
-%INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F5_ACCF2C4_STENCIL_17_BC_6_24
-%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F5_ACCF2C4_STENCIL_17_BC_6_24
-
-%    This function was generated by the Symbolic Math Toolbox version 8.0.
-%    21-May-2018 15:35:39
-
-stencil_F2C = [-2.564929780505952e-4,-1.220703125e-3,2.051943824404762e-3,1.1962890625e-2,-7.181803385416667e-3,-5.9814453125e-2,1.436360677083333e-2,2.99072265625e-1,4.820454915364583e-1,2.99072265625e-1,1.436360677083333e-2,-5.9814453125e-2,-7.181803385416667e-3,1.1962890625e-2,2.051943824404762e-3,-1.220703125e-3,-2.564929780505952e-4];
-if nargout > 1
-    BC_F2C = reshape([-1.673327822994457e1,1.665420585653232e1,-1.973927473454954e2,2.826257908914756e1,-6.156813484052936e1,3.974966126696054,2.880639373222355e1,-2.660797294399895e1,3.202303847857831e2,-4.598960974033412e1,1.003152507870138e2,-6.481221721577338,8.061874893005659,-7.706608975219419,9.234201483040626e1,-1.322147613066874e1,2.880209985918895e1,-1.859523138300886,-2.19528557898034e1,2.13763239391502e1,-2.476320412310993e2,3.572924955195535e1,-7.795290920161567e1,5.036097395109802,-1.287197329845376,1.244100160910233,-1.394684346537857e1,2.112320869857597,-4.60441856527933,2.978264879234002e-1,1.935199269380359,-1.88580031845933,2.330807783420723e1,-2.91749306966336,6.644427567385864,-4.302395355488564e-1,-1.148984264037686,1.109982778464842,-1.314799057941425e1,2.137017065505111,-4.084082382904703,2.606486561845403e-1,1.565462612018858,-1.508309105065004,1.772442871757061e1,-2.40060893717649,6.31422909250156,-4.052444871368164e-1,3.179380137695096e-1,-3.071741522636364e-1,3.636264382483117,-5.183996466001354e-1,2.322192602480252,-6.467931586900172e-2,6.277081831671831e-1,-6.107890751034906e-1,7.335850436798604,-1.091016872160133,3.089218691662174,6.988892111841499e-2,1.639756762532723,-1.583883992641009,1.876236237708381e1,-2.685390559486947,5.859855615166555,3.919312696253764e-3,1.611803934956753,-1.540778869185931,1.795955382224485e1,-2.495154500270907,5.003492494640851,-4.157919873785453e-2,-6.213413520816026e-1,6.242581523412814e-1,-7.823535324240331,1.222418137438074,-3.120142966701915,2.975831327541895e-1,2.12230710100161,-2.0451058741188,2.412395225004063e1,-3.423544496956294,7.325914828631551,-4.793445914188063e-1,-4.31809447483846,4.158975059021769,-4.906211424150023e1,6.975058620124194,-1.501259943091044e1,9.418983630154896e-1,-6.138797742037704e-1,5.810969368378602e-1,-6.6821474226667,9.113864351863538e-1,-1.814400062103318,1.002574935832871e-1,-9.860044240994036e-2,9.448685284232805e-2,-1.106188847377502,1.552858946803229e-1,-3.265426230113952e-1,2.062042480203908e-2,-2.745034502159738,2.655226942873441,-3.151193386341271e1,4.520932327069998,-9.883338555855938,6.423439846307804e-1,2.139968493382333,-2.067738462547628,2.450223844197562e1,-3.50699574523559,7.635005983192545,-4.923960464980415e-1,1.036406872394752,-1.002008838408551,1.188339891704641e1,-1.70302259679446,3.715789696036691,-2.407301455417931e-1,1.606428513214277,-1.552524985439685,1.840245870449254e1,-2.635131753653705,5.741508438443495,-3.708346905830083e-1,5.659562678739624e-2,-5.465656201303744e-2,6.471932864664631e-1,-9.253169145609999e-2,2.010909570941804e-1,-1.292046400706276e-2,5.435391241988039e-1,-5.252672844681129e-1,6.225561585258754,-8.91344337215917e-1,1.941632399616401,-1.253426955105431e-1,-1.552116972709218,1.499962759958308,-1.777819805127299e1,2.545472086708348,-5.545140384142844,3.580057322157566e-1],[6,24]);
-end
-if nargout > 2
-    t2 = [2.948906761778786e-1,1.525720623897707,2.57452876984127e-1,1.798113701499118,4.127080577601411e-1,1.278484623015873,9.232955798059965e-1,1.009333860859158];
-    HcU = t2;
-end
-if nargout > 3
-    HfU = t2;
-end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_2to2_ratio2to1.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,47 @@
+function [IC2F,IF2C,Hc,Hf] = IntOpOP_orders_2to2_ratio2to1(mc,hc,ACC)
+
+% ACC is a string.
+% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
+% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
+ratio = 2;
+mf = ratio*mc-1;
+hf = hc/ratio;
+
+switch ACC
+    case 'F2C'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_2to2_ratio_2to1_accC2F1_accF2C2;
+    case 'C2F'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_2to2_ratio_2to1_accC2F2_accF2C1;
+end
+
+stencil_width = length(stencil_F2C);
+stencil_hw = (stencil_width-1)/2;
+[BC_rows,BC_cols] = size(BC_F2C);
+
+%%% Norm matrices %%%
+Hc = speye(mc,mc);
+HcUm = length(HcU);
+Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
+Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
+Hc = Hc*hc;
+
+Hf = speye(mf,mf);
+HfUm = length(HfU);
+Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
+Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
+Hf = Hf*hf;
+%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IF2C from stencil and BC
+IF2C = sparse(mc,mf);
+for i = BC_rows+1 : mc-BC_rows
+    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
+end
+IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
+IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IC2F using symmetry condition %%%%
+IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_2to2_ratio_2to1_accC2F1_accF2C2.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,17 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_2to2_ratio_2to1_accC2F1_accF2C2
+%INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F1_ACCF2C2_STENCIL_5_BC_2_5
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F1_ACCF2C2_STENCIL_5_BC_2_5
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:36:07
+
+stencil_F2C = [-1.0./8.0,1.0./4.0,3.0./4.0,1.0./4.0,-1.0./8.0];
+if nargout > 1
+    BC_F2C = reshape([6.288191560529559e-1,-6.440957802647795e-2,6.855471317807184e-1,1.572264341096408e-1,-2.438028498638558e-1,7.469014249319279e-1,-8.431231982626708e-2,2.921561599131335e-1,1.374888185644862e-2,-1.318744409282243e-1],[2,5]);
+end
+if nargout > 2
+    HcU = 1.0./2.0;
+end
+if nargout > 3
+    HfU = 1.0./2.0;
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_2to2_ratio_2to1_accC2F2_accF2C1.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,17 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_2to2_ratio_2to1_accC2F2_accF2C1
+%INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F2_ACCF2C1_STENCIL_5_BC_1_3
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_2TO2_RATIO_2TO1_ACCC2F2_ACCF2C1_STENCIL_5_BC_1_3
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:36:08
+
+stencil_F2C = [1.0./4.0,1.0./2.0,1.0./4.0];
+if nargout > 1
+    BC_F2C = [1.0./2.0,1.0./2.0];
+end
+if nargout > 2
+    HcU = 1.0./2.0;
+end
+if nargout > 3
+    HfU = 1.0./2.0;
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_4to4_ratio2to1.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,47 @@
+function [IC2F,IF2C,Hc,Hf] = IntOpOP_orders_4to4_ratio2to1(mc,hc,ACC)
+
+% ACC is a string.
+% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
+% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
+ratio = 2;
+mf = ratio*mc-1;
+hf = hc/ratio;
+
+switch ACC
+    case 'F2C'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_4to4_ratio_2to1_accC2F2_accF2C3;
+    case 'C2F'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_4to4_ratio_2to1_accC2F3_accF2C2;
+end
+
+stencil_width = length(stencil_F2C);
+stencil_hw = (stencil_width-1)/2;
+[BC_rows,BC_cols] = size(BC_F2C);
+
+%%% Norm matrices %%%
+Hc = speye(mc,mc);
+HcUm = length(HcU);
+Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
+Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
+Hc = Hc*hc;
+
+Hf = speye(mf,mf);
+HfUm = length(HfU);
+Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
+Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
+Hf = Hf*hf;
+%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IF2C from stencil and BC
+IF2C = sparse(mc,mf);
+for i = BC_rows+1 : mc-BC_rows
+    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
+end
+IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
+IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IC2F using symmetry condition %%%%
+IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_4to4_ratio_2to1_accC2F2_accF2C3.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,18 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_4to4_ratio_2to1_accC2F2_accF2C3
+%INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F2_ACCF2C3_STENCIL_9_BC_3_11
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F2_ACCF2C3_STENCIL_9_BC_3_11
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:36:01
+
+stencil_F2C = [7.0./2.56e2,-1.0./3.2e1,-7.0./6.4e1,9.0./3.2e1,8.5e1./1.28e2,9.0./3.2e1,-7.0./6.4e1,-1.0./3.2e1,7.0./2.56e2];
+if nargout > 1
+    BC_F2C = reshape([7.523257802630956e-2,2.447812262221267e-1,-1.679313063616916e-1,1.290510950666589,6.315723344677289e-3,1.67178747937954e-1,1.982667903557025,-7.554383893379468e-1,7.215271362899867e-1,-2.820478831383137,1.807034411305536,-7.589683751979843e-1,-7.685973268458095e-1,3.965751544535173e-1,4.119789638051451e-1,1.574000556785898e-1,-1.113618964927466e-1,3.631000220124657e-1,1.639694219982991,-9.114074742274862e-1,4.952715520862987e-1,-4.524162151353456e-1,2.65481378213589e-1,-2.268273408674622e-1,3.455365956773523e-1,-2.009765975089827e-1,1.722179564305811e-1,-5.52933488235368e-1,3.18109976271229e-1,-2.171481232558432e-1,1.033835580108027e-1,-5.911351224351343e-2,3.960076712054991e-2],[3,11]);
+end
+if nargout > 2
+    t2 = [1.7e1./4.8e1,5.9e1./4.8e1,4.3e1./4.8e1,4.9e1./4.8e1];
+    HcU = t2;
+end
+if nargout > 3
+    HfU = t2;
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_4to4_ratio_2to1_accC2F3_accF2C2.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,18 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_4to4_ratio_2to1_accC2F3_accF2C2
+%INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F3_ACCF2C2_STENCIL_9_BC_3_11
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_4TO4_RATIO_2TO1_ACCC2F3_ACCF2C2_STENCIL_9_BC_3_11
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:36:05
+
+stencil_F2C = [-1.0./2.56e2,-1.0./3.2e1,1.0./6.4e1,9.0./3.2e1,6.1e1./1.28e2,9.0./3.2e1,1.0./6.4e1,-1.0./3.2e1,-1.0./2.56e2];
+if nargout > 1
+    BC_F2C = reshape([1.0./2.0,0.0,0.0,1.77e2./2.72e2,3.0./8.0,-5.9e1./6.88e2,1.125919117647059e-2,3.546742584745763e-1,1.335392441860465e-2,-4.9e1./5.44e2,2.335805084745763e-1,3.204941860465116e-1,-1.194852941176471e-2,1.350635593220339e-2,5.308866279069767e-1,-9.0./5.44e2,-1.11228813559322e-2,2.943313953488372e-1,-2.803308823529412e-2,2.105402542372881e-2,-1.580668604651163e-2,-9.0./5.44e2,1.430084745762712e-2,-5.450581395348837e-2,-9.191176470588235e-4,7.944915254237288e-4,-5.450581395348837e-3,1.0./5.44e2,-1.588983050847458e-3,2.180232558139535e-3,2.297794117647059e-4,-1.986228813559322e-4,2.725290697674419e-4],[3,11]);
+end
+if nargout > 2
+    t2 = [1.7e1./4.8e1,5.9e1./4.8e1,4.3e1./4.8e1,4.9e1./4.8e1];
+    HcU = t2;
+end
+if nargout > 3
+    HfU = t2;
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_6to6_ratio2to1.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,47 @@
+function [IC2F,IF2C,Hc,Hf] = IntOpOP_orders_6to6_ratio2to1(mc,hc,ACC)
+
+% ACC is a string.
+% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
+% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
+ratio = 2;
+mf = ratio*mc-1;
+hf = hc/ratio;
+
+switch ACC
+    case 'F2C'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_6to6_ratio_2to1_accC2F3_accF2C4;
+    case 'C2F'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_6to6_ratio_2to1_accC2F4_accF2C3;
+end
+
+stencil_width = length(stencil_F2C);
+stencil_hw = (stencil_width-1)/2;
+[BC_rows,BC_cols] = size(BC_F2C);
+
+%%% Norm matrices %%%
+Hc = speye(mc,mc);
+HcUm = length(HcU);
+Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
+Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
+Hc = Hc*hc;
+
+Hf = speye(mf,mf);
+HfUm = length(HfU);
+Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
+Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
+Hf = Hf*hf;
+%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IF2C from stencil and BC
+IF2C = sparse(mc,mf);
+for i = BC_rows+1 : mc-BC_rows
+    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
+end
+IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
+IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IC2F using symmetry condition %%%%
+IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_6to6_ratio_2to1_accC2F3_accF2C4.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,18 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_6to6_ratio_2to1_accC2F3_accF2C4
+%INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F3_ACCF2C4_STENCIL_13_BC_3_17
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F3_ACCF2C4_STENCIL_13_BC_3_17
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:35:47
+
+stencil_F2C = [-5.95703125e-3,3.0./5.12e2,3.57421875e-2,-2.5e1./5.12e2,-8.935546875e-2,7.5e1./2.56e2,3.17e2./5.12e2,7.5e1./2.56e2,-8.935546875e-2,-2.5e1./5.12e2,3.57421875e-2,3.0./5.12e2,-5.95703125e-3];
+if nargout > 1
+    BC_F2C = reshape([5.233890618131365e-1,-1.594459192645467e-2,3.532688727637403e-2,8.021234957689208e-1,3.90683205173562e-1,-1.73222951632239e-1,-8.87662686483442e-2,2.90091235796637e-1,-1.600356115709148e-1,-1.044025375027475e-1,2.346179009198368e-1,6.091329306528956e-1,1.561275522703128e-1,-1.168382445709856e-1,1.040987887887311,-2.387061036980731e-1,1.363504965974361e-1,1.082611928255256e-1,-5.745310654054326e-1,3.977694249198785e-1,-9.376217911402619e-1,3.554518646054656e-2,5.609157787396987e-5,-1.564625311232018e-1,6.107907974027401e-1,-3.786608696698368e-1,7.02265869951125e-1,2.054294270642538e-1,-1.302300112378257e-1,2.478941407690889e-1,-2.657085326191479e-1,1.568761445933572e-1,-2.632906518005349e-1,-1.228047556139644e-1,7.182193248980271e-2,-1.1291238242346e-1,5.811258780405158e-2,-3.466364400805378e-2,5.683680203338252e-2,1.781337575097077e-2,-1.030572999042704e-2,1.577197067502767e-2,-1.443802115768554e-2,8.391316308374261e-3,-1.29534117369052e-2,-1.548018627738296e-3,8.794183904936319e-4,-1.298961407229805e-3,1.573818938200601e-3,-8.940753636685258e-4,1.320610764016968e-3],[3,17]);
+end
+if nargout > 2
+    t2 = [3.159490740740741e-1,1.390393518518519,6.275462962962963e-1,1.240509259259259,9.116898148148148e-1,1.013912037037037];
+    HcU = t2;
+end
+if nargout > 3
+    HfU = t2;
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_6to6_ratio_2to1_accC2F4_accF2C3.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,18 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_6to6_ratio_2to1_accC2F4_accF2C3
+%INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F4_ACCF2C3_STENCIL_13_BC_4_17
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_6TO6_RATIO_2TO1_ACCC2F4_ACCF2C3_STENCIL_13_BC_4_17
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:35:56
+
+stencil_F2C = [1.07421875e-3,3.0./5.12e2,-6.4453125e-3,-2.5e1./5.12e2,1.611328125e-2,7.5e1./2.56e2,2.45e2./5.12e2,7.5e1./2.56e2,1.611328125e-2,-2.5e1./5.12e2,-6.4453125e-3,3.0./5.12e2,1.07421875e-3];
+if nargout > 1
+    BC_F2C = reshape([1.0./2.0,0.0,0.0,0.0,6.876076086160158e-1,1.5e1./3.2e1,-3.461879841386942e-1,3.502577439820862e-2,3.099721991995751e-3,2.228547003766753e-1,9.363652999354482e-3,-3.15791046603844e-3,-1.05789143206462e-1,2.35563165945226e-1,6.070385985337514e-1,-4.847496617839149e-2,-4.809232246867902e-3,5.154694068405061e-3,7.049223649022501e-1,1.016749349808733e-2,3.460117842882262e-2,-4.996621498584866e-2,5.210650763094799e-1,2.233592875303228e-1,-2.239024779745769e-3,4.254668119953384e-4,9.213872590833641e-3,3.910524351558127e-1,-9.048711215107334e-2,8.597375629526346e-2,-3.468219752858724e-1,3.250682992395969e-1,-1.309107466664224e-1,1.199249722306043e-1,-4.071552384959425e-1,1.474417123938701e-1,-3.02863877390285e-2,3.046016554982103e-2,-1.081315128181483e-1,1.120705238850532e-2,7.977722870036266e-2,-6.772545887788229e-2,2.00270418837606e-1,-5.427183680490763e-2,6.524845570188292e-2,-5.637610037043203e-2,1.711235764016968e-1,-4.203646902407166e-2,4.639548341453586e-3,-4.055884445496545e-3,1.258630924935448e-2,-2.776451559292779e-3,-1.023784366070774e-2,8.817108288936985e-3,-2.659664906860937e-2,7.14445034054861e-3,-1.435466025441424e-3,1.240274208149505e-3,-3.764718680837329e-3,1.028716295017727e-3,1.032012418492197e-3,-8.794183904936319e-4,2.597922814459609e-3,-6.571159498040679e-4,1.892022767235695e-4,-1.612267049238325e-4,4.76285849317595e-4,-1.204712574640791e-4],[4,17]);
+end
+if nargout > 2
+    t2 = [3.159490740740741e-1,1.390393518518519,6.275462962962963e-1,1.240509259259259,9.116898148148148e-1,1.013912037037037];
+    HcU = t2;
+end
+if nargout > 3
+    HfU = t2;
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_8to8_ratio2to1.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,47 @@
+function [IC2F,IF2C,Hc,Hf] = IntOpOP_orders_8to8_ratio2to1(mc,hc,ACC)
+
+% ACC is a string.
+% ACC = 'C2F' creates IC2F with one order of accuracy higher than IF2C.
+% ACC = 'F2C' creates IF2C with one order of accuracy higher than IC2F.
+ratio = 2;
+mf = ratio*mc-1;
+hf = hc/ratio;
+
+switch ACC
+    case 'F2C'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_8to8_ratio_2to1_accC2F4_accF2C5;
+    case 'C2F'
+        [stencil_F2C,BC_F2C,HcU,HfU] = ...
+        sbp.implementations.intOpOP_orders_8to8_ratio_2to1_accC2F5_accF2C4;
+end
+
+stencil_width = length(stencil_F2C);
+stencil_hw = (stencil_width-1)/2;
+[BC_rows,BC_cols] = size(BC_F2C);
+
+%%% Norm matrices %%%
+Hc = speye(mc,mc);
+HcUm = length(HcU);
+Hc(1:HcUm,1:HcUm) = spdiags(HcU',0,HcUm,HcUm);
+Hc(mc-HcUm+1:mc,mc-HcUm+1:mc) = spdiags(rot90(HcU',2),0,HcUm,HcUm);
+Hc = Hc*hc;
+
+Hf = speye(mf,mf);
+HfUm = length(HfU);
+Hf(1:HfUm,1:HfUm) = spdiags(HfU',0,HfUm,HfUm);
+Hf(mf-length(HfU)+1:mf,mf-length(HfU)+1:mf) = spdiags(rot90(HfU',2),0,HfUm,HfUm);
+Hf = Hf*hf;
+%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IF2C from stencil and BC
+IF2C = sparse(mc,mf);
+for i = BC_rows+1 : mc-BC_rows
+    IF2C(i,ratio*i-1+(-stencil_hw:stencil_hw)) = stencil_F2C; %#ok<SPRIX>
+end
+IF2C(1:BC_rows,1:BC_cols) = BC_F2C;
+IF2C(end-BC_rows+1:end,end-BC_cols+1:end) = rot90(BC_F2C,2);
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%% Create IC2F using symmetry condition %%%%
+IC2F = Hf\IF2C.'*Hc;
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_8to8_ratio_2to1_accC2F4_accF2C5.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,18 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_8to8_ratio_2to1_accC2F4_accF2C5
+%INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F4_ACCF2C5_STENCIL_17_BC_5_24
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F4_ACCF2C5_STENCIL_17_BC_5_24
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:35:02
+
+stencil_F2C = [1.324608212425595e-3,-1.220703125e-3,-1.059686569940476e-2,1.1962890625e-2,3.708902994791667e-2,-5.9814453125e-2,-7.417805989583333e-2,2.99072265625e-1,5.927225748697917e-1,2.99072265625e-1,-7.417805989583333e-2,-5.9814453125e-2,3.708902994791667e-2,1.1962890625e-2,-1.059686569940476e-2,-1.220703125e-3,1.324608212425595e-3];
+if nargout > 1
+    BC_F2C = reshape([2.087365925359584,-1.227221822236823,1.090916714284468e1,-1.041312149906314,1.134214373258162,-1.269686811479259,2.075368250436277,-1.520771409696474e1,1.389750473974189,-1.48485748783569,-1.040579640776707,8.899721508624742e-1,-7.177691661032869,6.882712043721976e-1,-7.599347599660409e-1,-1.26440526850463,1.160658043364166,-5.391509178445742,6.679923135342851e-1,-7.521725463922262e-1,3.752349810676949,-2.906684049793639,2.672876913566556e1,-2.493145660873,2.782825829667436,1.443588084644871e-1,-1.307230271348211e-1,2.216804748506809,1.437719804483573e-1,-1.145830952112369e-1,3.2149320801083e-1,-2.34361439272989e-1,1.855837403850803,1.286992417665136e-1,-5.758238484341108e-2,-1.301103772185027,9.973408313121463e-1,-8.837520107531879,9.534930382604288e-1,-1.429199518808459e-2,-2.384453600787036,1.818345997558567,-1.577342441239303e1,1.422846302346762,3.154159322410927e-3,3.589377915408905e-1,-2.109524979864723e-1,9.363227187483732e-1,6.301238593470628e-2,5.732390257964316e-2,2.793582225299658,-2.033528056927806,1.621324028555783e1,-1.189222718426265,6.189671387692164e-2,5.342131492864642e-1,-4.222231296997605e-1,3.787253511209165,-3.350064226195165e-1,1.245325350855226e-2,-2.184146687275183,1.551331905163865,-1.19387312118926e1,8.349589004472998e-1,-1.35383591594438e-1,-8.014367493869704e-1,5.668415377001197e-1,-4.302842643863972,2.84183319528176e-1,3.83514596570461e-2,9.45794880458861e-1,-6.732638898386457e-1,5.234390273661413,-3.83498639699941e-1,1.440453495443018e-1,5.645065377027613e-1,-4.039220855868618e-1,3.170156487564899,-2.383074337879712e-1,1.216617375214008e-1,-1.937863224145611e-1,1.358891032584724e-1,-1.023378722711107,6.830621267493578e-2,-4.169135139842575e-3,2.270306426219975e-2,-2.38399209865252e-2,2.928388757260058e-1,-4.02060181933195e-2,6.880595419697505e-2,9.638828970166005e-2,-6.98778025332229e-2,5.609317796857676e-1,-4.429526993510467e-2,2.882554468024363e-2,3.582431391759518e-2,-2.671910644265286e-2,2.251335440088556e-1,-1.966486325944329e-2,1.791756577091828e-2,-3.350790201878844e-1,2.581411034605136e-1,-2.283079071439122,2.162064132948073e-1,-2.321676317817421e-1,6.356644993195555e-2,-4.921907141164279e-2,4.384534411523264e-1,-4.198474091936761e-2,4.597203884996652e-2,2.261662512481835e-2,-1.740429407604355e-2,1.537038474929879e-1,-1.452709057733876e-2,1.556101844926456e-2,3.097679325854209e-2,-2.394872918869654e-2,2.128879105995857e-1,-2.032077838507769e-2,2.213372706946953e-2],[5,24]);
+end
+if nargout > 2
+    t2 = [2.948906761778786e-1,1.525720623897707,2.57452876984127e-1,1.798113701499118,4.127080577601411e-1,1.278484623015873,9.232955798059965e-1,1.009333860859158];
+    HcU = t2;
+end
+if nargout > 3
+    HfU = t2;
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/intOpOP_orders_8to8_ratio_2to1_accC2F5_accF2C4.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,18 @@
+function [stencil_F2C,BC_F2C,HcU,HfU] = intOpOP_orders_8to8_ratio_2to1_accC2F5_accF2C4
+%INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F5_ACCF2C4_STENCIL_17_BC_6_24
+%    [STENCIL_F2C,BC_F2C,HCU,HFU] = INT_ORDERS_8TO8_RATIO_2TO1_ACCC2F5_ACCF2C4_STENCIL_17_BC_6_24
+
+%    This function was generated by the Symbolic Math Toolbox version 8.0.
+%    21-May-2018 15:35:39
+
+stencil_F2C = [-2.564929780505952e-4,-1.220703125e-3,2.051943824404762e-3,1.1962890625e-2,-7.181803385416667e-3,-5.9814453125e-2,1.436360677083333e-2,2.99072265625e-1,4.820454915364583e-1,2.99072265625e-1,1.436360677083333e-2,-5.9814453125e-2,-7.181803385416667e-3,1.1962890625e-2,2.051943824404762e-3,-1.220703125e-3,-2.564929780505952e-4];
+if nargout > 1
+    BC_F2C = reshape([-1.673327822994457e1,1.665420585653232e1,-1.973927473454954e2,2.826257908914756e1,-6.156813484052936e1,3.974966126696054,2.880639373222355e1,-2.660797294399895e1,3.202303847857831e2,-4.598960974033412e1,1.003152507870138e2,-6.481221721577338,8.061874893005659,-7.706608975219419,9.234201483040626e1,-1.322147613066874e1,2.880209985918895e1,-1.859523138300886,-2.19528557898034e1,2.13763239391502e1,-2.476320412310993e2,3.572924955195535e1,-7.795290920161567e1,5.036097395109802,-1.287197329845376,1.244100160910233,-1.394684346537857e1,2.112320869857597,-4.60441856527933,2.978264879234002e-1,1.935199269380359,-1.88580031845933,2.330807783420723e1,-2.91749306966336,6.644427567385864,-4.302395355488564e-1,-1.148984264037686,1.109982778464842,-1.314799057941425e1,2.137017065505111,-4.084082382904703,2.606486561845403e-1,1.565462612018858,-1.508309105065004,1.772442871757061e1,-2.40060893717649,6.31422909250156,-4.052444871368164e-1,3.179380137695096e-1,-3.071741522636364e-1,3.636264382483117,-5.183996466001354e-1,2.322192602480252,-6.467931586900172e-2,6.277081831671831e-1,-6.107890751034906e-1,7.335850436798604,-1.091016872160133,3.089218691662174,6.988892111841499e-2,1.639756762532723,-1.583883992641009,1.876236237708381e1,-2.685390559486947,5.859855615166555,3.919312696253764e-3,1.611803934956753,-1.540778869185931,1.795955382224485e1,-2.495154500270907,5.003492494640851,-4.157919873785453e-2,-6.213413520816026e-1,6.242581523412814e-1,-7.823535324240331,1.222418137438074,-3.120142966701915,2.975831327541895e-1,2.12230710100161,-2.0451058741188,2.412395225004063e1,-3.423544496956294,7.325914828631551,-4.793445914188063e-1,-4.31809447483846,4.158975059021769,-4.906211424150023e1,6.975058620124194,-1.501259943091044e1,9.418983630154896e-1,-6.138797742037704e-1,5.810969368378602e-1,-6.6821474226667,9.113864351863538e-1,-1.814400062103318,1.002574935832871e-1,-9.860044240994036e-2,9.448685284232805e-2,-1.106188847377502,1.552858946803229e-1,-3.265426230113952e-1,2.062042480203908e-2,-2.745034502159738,2.655226942873441,-3.151193386341271e1,4.520932327069998,-9.883338555855938,6.423439846307804e-1,2.139968493382333,-2.067738462547628,2.450223844197562e1,-3.50699574523559,7.635005983192545,-4.923960464980415e-1,1.036406872394752,-1.002008838408551,1.188339891704641e1,-1.70302259679446,3.715789696036691,-2.407301455417931e-1,1.606428513214277,-1.552524985439685,1.840245870449254e1,-2.635131753653705,5.741508438443495,-3.708346905830083e-1,5.659562678739624e-2,-5.465656201303744e-2,6.471932864664631e-1,-9.253169145609999e-2,2.010909570941804e-1,-1.292046400706276e-2,5.435391241988039e-1,-5.252672844681129e-1,6.225561585258754,-8.91344337215917e-1,1.941632399616401,-1.253426955105431e-1,-1.552116972709218,1.499962759958308,-1.777819805127299e1,2.545472086708348,-5.545140384142844,3.580057322157566e-1],[6,24]);
+end
+if nargout > 2
+    t2 = [2.948906761778786e-1,1.525720623897707,2.57452876984127e-1,1.798113701499118,4.127080577601411e-1,1.278484623015873,9.232955798059965e-1,1.009333860859158];
+    HcU = t2;
+end
+if nargout > 3
+    HfU = t2;
+end
--- a/+sbp/InterpAWW.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,68 +0,0 @@
-classdef InterpAWW < sbp.InterpOps
-    properties
-
-        % Interpolation operators
-        IC2F
-        IF2C
-
-        % Orders used on coarse and fine sides
-        order_C
-        order_F
-
-        % Grid points, refinement ratio.
-        ratio
-        m_C
-        m_F
-
-        % Boundary accuracy of IC2F and IF2C.
-        acc_C2F
-        acc_F2C
-    end
-
-    methods
-        % accOp : String, 'C2F' or 'F2C'. Specifies which of the operators
-        % should have higher accuracy.
-        function obj = InterpAWW(m_C,m_F,order_C,order_F,accOp)
-            assertIsMember(accOp, {'C2F','F2C'});
-
-            ratio = (m_F-1)/(m_C-1);
-            h_C = 1;
-
-            assert(order_C == order_F,...
-                    'Error: Different orders of accuracy not available');
-
-            switch ratio
-            case 2
-                switch order_C
-                case 2
-                    [IC2F,IF2C] = sbp.implementations.intOpAWW_orders_2to2_ratio2to1(m_C, h_C, accOp);
-                case 4
-                    [IC2F,IF2C] = sbp.implementations.intOpAWW_orders_4to4_ratio2to1(m_C, h_C, accOp);
-                case 6
-                    [IC2F,IF2C] = sbp.implementations.intOpAWW_orders_6to6_ratio2to1(m_C, h_C, accOp);
-                case 8
-                    [IC2F,IF2C] = sbp.implementations.intOpAWW_orders_8to8_ratio2to1(m_C, h_C, accOp);
-                otherwise
-                    error(['Order ' num2str(order_C) ' not available.']);
-                end
-            otherwise
-                error(['Grid ratio ' num2str(ratio) ' not available']);
-            end
-
-            obj.IC2F = IC2F;
-            obj.IF2C = IF2C;
-            obj.order_C = order_C;
-            obj.order_F = order_F;
-            obj.ratio = ratio;
-            obj.m_C = m_C;
-            obj.m_F = m_F;
-
-        end
-
-        function str = string(obj)
-            str = [class(obj) '_orders' num2str(obj.order_F) 'to'...
-            num2str(obj.order_C) '_ratio' num2str(obj.ratio) 'to1'];
-        end
-
-    end
-end
--- a/+sbp/InterpMC.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,61 +0,0 @@
-classdef InterpMC < sbp.InterpOps
-    properties
-
-        % Interpolation operators
-        IC2F
-        IF2C
-
-        % Orders used on coarse and fine sides
-        order_C
-        order_F
-
-        % Grid points, refinement ratio.
-        ratio
-        m_C
-        m_F
-    end
-
-    methods
-        function obj = InterpMC(m_C,m_F,order_C,order_F)
-
-            ratio = (m_F-1)/(m_C-1);
-
-            assert(order_C == order_F,...
-                    'Error: Different orders of accuracy not available');
-
-            switch ratio
-            case 2
-                switch order_C
-                case 2
-                    [IC2F,IF2C] = sbp.implementations.intOpMC_orders_2to2_ratio2to1(m_C);
-                case 4
-                    [IC2F,IF2C] = sbp.implementations.intOpMC_orders_4to4_ratio2to1(m_C);
-                case 6
-                    [IC2F,IF2C] = sbp.implementations.intOpMC_orders_6to6_ratio2to1(m_C);
-                case 8
-                    [IC2F,IF2C] = sbp.implementations.intOpMC_orders_8to8_ratio2to1(m_C);
-                otherwise
-                    error(['Order ' num2str(order_C) ' not available.']);
-                end
-            otherwise
-                error(['Grid ratio ' num2str(ratio) ' not available']);
-            end
-
-            obj.IC2F = IC2F;
-            obj.IF2C = IF2C;
-            obj.order_C = order_C;
-            obj.order_F = order_F;
-            obj.ratio = ratio;
-            obj.m_C = m_C;
-            obj.m_F = m_F;
-
-
-        end
-
-        function str = string(obj)
-            str = [class(obj) '_orders' num2str(obj.order_F) 'to'...
-            num2str(obj.order_C) '_ratio' num2str(obj.ratio) 'to1'];
-        end
-
-    end
-end
--- a/+sbp/InterpOps.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+sbp/InterpOps.m	Tue Feb 12 17:12:42 2019 +0100
@@ -1,9 +1,7 @@
 classdef (Abstract) InterpOps
     properties (Abstract)
-        % C and F may refer to coarse and fine, but it's not a must.
-        IC2F % Interpolation operator from "C" to "F"
-        IF2C % Interpolation operator from "F" to "C"
-
+        Iu2v % Interpolation operator(s) from "u" to "v"
+        Iv2u % Interpolation operator(s) from "v" to "u"
     end
 
     methods (Abstract)
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/InterpOpsMC.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,78 @@
+% Interpolation operators by Mattsson and Carpenter (MC), see
+% Mattsson and Carpenter,
+% "Stable and Accurate Interpolatino Operators for High-Order Multiblock Finite DIfference Methods",
+% https://epubs.siam.org/doi/pdf/10.1137/090750068
+%
+% Let ^* denote the adjoint. These operators satsify
+%
+% Iuv2 = Iv2u^*
+%
+% Both Iu2v and Iv2u have p:th order accuracy, if the interior stencil is
+% of order 2p.
+%
+% This approach leads to a reduction of the convergence rate by one order for
+% PDEs with 2nd derivatives in space, as compared to conforming interfaces.
+% To obtain full convergence rate, use the order-preserving (OP) operators in
+% InterpOpsOP.m
+classdef InterpOpsMC < sbp.InterpOps
+    properties
+
+        % Structs of interpolation operators, fields .good and .bad
+        % Here .good and .bad are the same, but this makes them fit in the
+        % OP (order-preserving) framework.
+        Iu2v
+        Iv2u
+    end
+
+    methods
+        % m_u, m_v         --   number of grid points along the interface
+        % order_u, order_v --   order of accuracy in the different blocks
+        function obj = InterpOpsMC(m_u, m_v, order_u, order_v)
+
+            assert(order_u == order_v,...
+                    'InterpOpsMC: Different orders of accuracy not available');
+
+            switch order_u
+            case 2
+                intOpSet = @sbp.implementations.intOpMC_orders_2to2_ratio2to1;
+            case 4
+                intOpSet = @sbp.implementations.intOpMC_orders_4to4_ratio2to1;
+            case 6
+                intOpSet = @sbp.implementations.intOpMC_orders_6to6_ratio2to1;
+            case 8
+                intOpSet = @sbp.implementations.intOpMC_orders_8to8_ratio2to1;
+            otherwise
+                error('InterpOpsMC: Order of accuracy %d not available.', order_u);
+            end
+
+            Iu2v = struct;
+            Iv2u = struct;
+
+            if (m_u-1)/(m_v-1) == 2
+                % Block u is fine, v is coarse
+                m_C = m_v;
+                [Iv2u.good, Iu2v.bad] = intOpSet(m_C);
+                Iv2u.bad = Iv2u.good;
+                Iu2v.good = Iu2v.bad;
+
+            elseif (m_v-1)/(m_u-1) == 2
+                % Block v is fine, u is coarse
+                m_C = m_u;
+                [Iu2v.good, Iv2u.bad] = intOpSet(m_C);
+                Iu2v.bad = Iu2v.good;
+                Iv2u.good = Iv2u.bad;
+            else
+                error('InterpOpsMC: Interpolation operators for grid ratio %f have not yet been constructed', (m_u-1)/(m_v-1));
+            end
+
+            obj.Iu2v = Iu2v;
+            obj.Iv2u = Iv2u;
+
+        end
+
+        function str = string(obj)
+            str = [class(obj)];
+        end
+
+    end
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/InterpOpsOP.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,76 @@
+% Order-preserving (OP) interpolation operators, see
+% Almquist, Wang, Werpers,
+% "Order-Preserving Interpolation for Summation-by-Parts Operators
+% at Non-Conforming Interfaces", https://arxiv.org/abs/1806.01931
+%
+% Let ^* denote the adjoint. These operators satsify
+%
+% Iuv2.good = Iv2u.bad^*
+% Iv2u.good = Iu2v.bad^*
+%
+% The .bad operators have the same order of accuracy as the operators
+% by Mattsson and Carpenter (MC) in InterpOpsMC, i.e. order p,
+% if the interior stencil is order 2p. The .good operators are
+% one order more accurate, i.e. order p+1.
+%
+% For PDEs of second order in space, the OP operators allow for the same
+% convergence rate as with conforming interfaces, which is an improvement
+% by one order compared what is possible with the MC operators.
+classdef InterpOpsOP < sbp.InterpOps
+    properties
+
+        % Structs of interpolation operators, fields .good and .bad
+        Iu2v
+        Iv2u
+    end
+
+    methods
+        % m_u, m_v         --   number of grid points along the interface
+        % order_u, order_v --   order of accuracy in the different blocks
+        function obj = InterpOpsOP(m_u, m_v, order_u, order_v)
+
+            assert(order_u == order_v,...
+                    'InterpOpsOP: Different orders of accuracy not available');
+
+            switch order_u
+            case 2
+                intOpSet = @sbp.implementations.intOpOP_orders_2to2_ratio2to1;
+            case 4
+                intOpSet = @sbp.implementations.intOpOP_orders_4to4_ratio2to1;
+            case 6
+                intOpSet = @sbp.implementations.intOpOP_orders_6to6_ratio2to1;
+            case 8
+                intOpSet = @sbp.implementations.intOpOP_orders_8to8_ratio2to1;
+            otherwise
+                error('InterpOpsOP: Order of accuracy %d not available.', order_u);
+            end
+
+            Iu2v = struct;
+            Iv2u = struct;
+
+            if (m_u-1)/(m_v-1) == 2
+                % Block u is fine, v is coarse
+                m_C = m_v;
+                [Iv2u.good, Iu2v.bad] = intOpSet(m_C, 1, 'C2F');
+                [Iv2u.bad, Iu2v.good] = intOpSet(m_C, 1, 'F2C');
+
+            elseif (m_v-1)/(m_u-1) == 2
+                % Block v is fine, u is coarse
+                m_C = m_u;
+                [Iu2v.good, Iv2u.bad] = intOpSet(m_C, 1, 'C2F');
+                [Iu2v.bad, Iv2u.good] = intOpSet(m_C, 1, 'F2C');
+            else
+                error('InterpOpsOP: Interpolation operators for grid ratio %f have not yet been constructed', (m_u-1)/(m_v-1));
+            end
+
+            obj.Iu2v = Iu2v;
+            obj.Iv2u = Iv2u;
+
+        end
+
+        function str = string(obj)
+            str = [class(obj)];
+        end
+
+    end
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+scheme/+bc/closureSetup.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,25 @@
+% Setup closure and penalty matrices for several boundary conditions at once.
+% Each bc is a struct with the fields
+%  * type     -- Type of boundary condition
+%  * boundary -- Boundary identifier
+%  * data     -- A function_handle for a function which provides boundary data.(see below)
+% Also takes S_sign which modifies the sign of the penalty function, [-1,1]
+% Returns a closure matrix and a penalty matrices for each boundary condition.
+%
+% The boundary data function can either be a function of time or a function of time and space coordinates.
+% In the case where it only depends on time it should return the data as grid function for the boundary.
+% In the case where it also takes space coordinates the number of space coordinates should match the number of dimensions of the problem domain.
+% For example in the 2D case: f(t,x,y).
+function [closure, penalties] = closureSetup(diffOp, bcs)
+    scheme.bc.verifyFormat(bcs, diffOp);
+
+    % Setup storage arrays
+    closure = spzeros(size(diffOp));
+    penalties = cell(1, length(bcs));
+
+    % Collect closures and penalties
+    for i = 1:length(bcs)
+        [localClosure, penalties{i}] = diffOp.boundary_condition(bcs{i}.boundary, bcs{i}.type);
+        closure = closure + localClosure;
+    end
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+scheme/+bc/forcingSetup.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,86 @@
+% Setup the forcing function for the given boundary conditions and data.
+% Each bc is a struct with the fields
+%  * type     -- Type of boundary condition
+%  * boundary -- Boundary identifier
+%  * data     -- A function_handle for a function which provides boundary data.(see below)
+% S_sign allows changing the sign of the function to put on different sides in the system of ODEs.
+%   default is 1, which the same side as the diffOp.
+% Returns a forcing function S.
+%
+% The boundary data function can either be a function of time or a function of time and space coordinates.
+% In the case where it only depends on time it should return the data as grid function for the boundary.
+% In the case where it also takes space coordinates the number of space coordinates should match the number of dimensions of the problem domain.
+% For example in the 2D case: f(t,x,y).
+
+function S = forcingSetup(diffOp, penalties, bcs, S_sign)
+    default_arg('S_sign', 1);
+
+    assertType(bcs, 'cell');
+    assertIsMember(S_sign, [1, -1]);
+
+    scheme.bc.verifyFormat(bcs, diffOp);
+
+    [gridData, symbolicData] = parseAndSortData(bcs, penalties, diffOp);
+
+    % Setup penalty function
+    O = spzeros(size(diffOp),1);
+    function v = S_fun(t)
+        v = O;
+        for i = 1:length(gridData)
+            v = v + gridData{i}.penalty*gridData{i}.func(t);
+        end
+
+        for i = 1:length(symbolicData)
+            v = v + symbolicData{i}.penalty*symbolicData{i}.func(t, symbolicData{i}.coords{:});
+        end
+
+        v = S_sign * v;
+    end
+    S = @S_fun;
+end
+
+% Go through a cell array of boundary condition specifications and return cell arrays
+% of structs for grid and symbolic data.
+function [gridData, symbolicData] = parseAndSortData(bcs, penalties, diffOp)
+    gridData = {};
+    symbolicData = {};
+    for i = 1:length(bcs)
+        [ok, isSymbolic, data] = parseData(bcs{i}, penalties{i}, diffOp.grid);
+
+        if ~ok
+            continue % There was no data
+        end
+
+        if isSymbolic
+            symbolicData{end+1} = data;
+        else
+            gridData{end+1} = data;
+        end
+    end
+end
+
+function [ok, isSymbolic, dataStruct] = parseData(bc, penalty, grid)
+    if ~isfield(bc,'data') || isempty(bc.data)
+        isSymbolic = [];
+        dataStruct = struct();
+        ok = false;
+        return
+    end
+    ok = true;
+
+    nArg = nargin(bc.data);
+
+    if nArg > 1
+        % Symbolic data
+        isSymbolic = true;
+        coord = grid.getBoundary(bc.boundary);
+        dataStruct.penalty = penalty;
+        dataStruct.func = bc.data;
+        dataStruct.coords = num2cell(coord, 1);
+    else
+        % Grid data
+        isSymbolic = false;
+        dataStruct.penalty = penalty;
+        dataStruct.func = bc.data;
+    end
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+scheme/+bc/verifyFormat.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,31 @@
+% Errors with a more or less detailed error message if there is a problem with the bc specification
+function verifyBcFormat(bcs, diffOp)
+    assertType(bcs, 'cell');
+    for i = 1:length(bcs)
+        assertType(bcs{i}, 'struct');
+        assertStructFields(bcs{i}, {'type', 'boundary'});
+
+        if ~isfield(bcs{i}, 'data') || isempty(bcs{i}.data)
+            continue
+        end
+
+        if ~isa(bcs{i}.data, 'function_handle')
+            error('bcs{%d}.data should be a function of time or a function of time and space',i);
+        end
+
+        % Find dimension of boundary
+        b = diffOp.grid.getBoundary(bcs{i}.boundary);
+        dim = size(b,2);
+
+        % Assert that the data function has a valid number of input arguments
+        if ~(nargin(bcs{i}.data) == 1 || nargin(bcs{i}.data) == 1 + dim)
+            error('sbplib:scheme:bcSetup:DataWrongNumberOfArguments', 'bcs{%d}.data has the wrong number of input arguments. Must be either only time or time and space.', i);
+        end
+
+        if nargin(bcs{i}.data) == 1
+            % Grid data (only function of time)
+            % Assert that the data has the correct dimension
+            assertSize(bcs{i}.data(0), 1, size(b,1));
+        end
+    end
+end
--- a/+scheme/Beam.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Beam.m	Tue Feb 12 17:12:42 2019 +0100
@@ -19,7 +19,7 @@
         alphaII
         alphaIII
 
-        opt
+        opt % TODO: Get rid of this and use the interface type instead
     end
 
     methods
@@ -86,7 +86,11 @@
         function [closure, penalty] = boundary_condition(obj,boundary,type)
             default_arg('type','dn');
 
-            [e, d1, d2, d3, s] = obj.get_boundary_ops(boundary);
+            e  = obj.getBoundaryOperator('e',  boundary);
+            d1 = obj.getBoundaryOperator('d1', boundary);
+            d2 = obj.getBoundaryOperator('d2', boundary);
+            d3 = obj.getBoundaryOperator('d3', boundary);
+            s = obj.getBoundarySign(boundary);
             gamm = obj.gamm;
             delt = obj.delt;
 
@@ -124,7 +128,7 @@
 
                     closure = obj.Hi*(tau*d2' + sig*d3');
                     penalty{1} = -obj.Hi*tau;
-                    penalty{1} = -obj.Hi*sig;
+                    penalty{2} = -obj.Hi*sig;
 
                 case 'e'
                     alpha = obj.alpha;
@@ -170,17 +174,24 @@
             end
         end
 
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
+        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary, type)
             % u denotes the solution in the own domain
             % v denotes the solution in the neighbour domain
-            [e_u,d1_u,d2_u,d3_u,s_u] = obj.get_boundary_ops(boundary);
-            [e_v,d1_v,d2_v,d3_v,s_v] = neighbour_scheme.get_boundary_ops(neighbour_boundary);
+            e_u  = obj.getBoundaryOperator('e',  boundary);
+            d1_u = obj.getBoundaryOperator('d1', boundary);
+            d2_u = obj.getBoundaryOperator('d2', boundary);
+            d3_u = obj.getBoundaryOperator('d3', boundary);
+            s_u = obj.getBoundarySign(boundary);
 
+            e_v  = neighbour_scheme.getBoundaryOperator('e',  neighbour_boundary);
+            d1_v = neighbour_scheme.getBoundaryOperator('d1', neighbour_boundary);
+            d2_v = neighbour_scheme.getBoundaryOperator('d2', neighbour_boundary);
+            d3_v = neighbour_scheme.getBoundaryOperator('d3', neighbour_boundary);
+            s_v = neighbour_scheme.getBoundarySign(neighbour_boundary);
 
             alpha_u = obj.alpha;
             alpha_v = neighbour_scheme.alpha;
 
-
             switch boundary
                 case 'l'
                     interface_opt = obj.opt.interface_l;
@@ -234,24 +245,37 @@
             penalty = -obj.Hi*(tau*e_v' + sig*d1_v' + phi*alpha_v*d2_v' + psi*alpha_v*d3_v');
         end
 
-        % Returns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
-        function [e, d1, d2, d3, s] = get_boundary_ops(obj,boundary)
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string
+        % boundary  -- string
+        function o = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(op, {'e', 'd1', 'd2', 'd3'})
+            assertIsMember(boundary, {'l', 'r'})
+
+            o = obj.([op, '_', boundary]);
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        % Note: for 1d diffOps, the boundary quadrature is the scalar 1.
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
+            H_b = 1;
+        end
+
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
             switch boundary
-                case 'l'
-                    e  = obj.e_l;
-                    d1 = obj.d1_l;
-                    d2 = obj.d2_l;
-                    d3 = obj.d3_l;
+                case {'r'}
+                    s = 1;
+                case {'l'}
                     s = -1;
-                case 'r'
-                    e  = obj.e_r;
-                    d1 = obj.d1_r;
-                    d2 = obj.d2_r;
-                    d3 = obj.d3_r;
-                    s = 1;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
             end
         end
 
--- a/+scheme/Beam2d.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,245 +0,0 @@
-classdef Beam2d < scheme.Scheme
-    properties
-        grid
-        order % Order accuracy for the approximation
-
-        D % non-stabalized scheme operator
-        M % Derivative norm
-        alpha
-
-        H % Discrete norm
-        Hi
-        H_x, H_y % Norms in the x and y directions
-        Hx,Hy % Kroneckerd norms. 1'*Hx*v corresponds to integration in the x dir.
-        Hi_x, Hi_y
-        Hix, Hiy
-        e_w, e_e, e_s, e_n
-        d1_w, d1_e, d1_s, d1_n
-        d2_w, d2_e, d2_s, d2_n
-        d3_w, d3_e, d3_s, d3_n
-        gamm_x, gamm_y
-        delt_x, delt_y
-    end
-
-    methods
-        function obj = Beam2d(m,lim,order,alpha,opsGen)
-            default_arg('alpha',1);
-            default_arg('opsGen',@sbp.Higher);
-
-            if ~isa(grid, 'grid.Cartesian') || grid.D() ~= 2
-                error('Grid must be 2d cartesian');
-            end
-
-            obj.grid = grid;
-            obj.alpha = alpha;
-            obj.order = order;
-
-            m_x = grid.m(1);
-            m_y = grid.m(2);
-
-            h = grid.scaling();
-            h_x = h(1);
-            h_y = h(2);
-
-            ops_x = opsGen(m_x,h_x,order);
-            ops_y = opsGen(m_y,h_y,order);
-
-            I_x = speye(m_x);
-            I_y = speye(m_y);
-
-            D4_x = sparse(ops_x.derivatives.D4);
-            H_x =  sparse(ops_x.norms.H);
-            Hi_x = sparse(ops_x.norms.HI);
-            e_l_x = sparse(ops_x.boundary.e_1);
-            e_r_x = sparse(ops_x.boundary.e_m);
-            d1_l_x = sparse(ops_x.boundary.S_1);
-            d1_r_x = sparse(ops_x.boundary.S_m);
-            d2_l_x  = sparse(ops_x.boundary.S2_1);
-            d2_r_x  = sparse(ops_x.boundary.S2_m);
-            d3_l_x  = sparse(ops_x.boundary.S3_1);
-            d3_r_x  = sparse(ops_x.boundary.S3_m);
-
-            D4_y = sparse(ops_y.derivatives.D4);
-            H_y =  sparse(ops_y.norms.H);
-            Hi_y = sparse(ops_y.norms.HI);
-            e_l_y = sparse(ops_y.boundary.e_1);
-            e_r_y = sparse(ops_y.boundary.e_m);
-            d1_l_y = sparse(ops_y.boundary.S_1);
-            d1_r_y = sparse(ops_y.boundary.S_m);
-            d2_l_y  = sparse(ops_y.boundary.S2_1);
-            d2_r_y  = sparse(ops_y.boundary.S2_m);
-            d3_l_y  = sparse(ops_y.boundary.S3_1);
-            d3_r_y  = sparse(ops_y.boundary.S3_m);
-
-
-            D4 = kr(D4_x, I_y) + kr(I_x, D4_y);
-
-            % Norms
-            obj.H = kr(H_x,H_y);
-            obj.Hx  = kr(H_x,I_x);
-            obj.Hy  = kr(I_x,H_y);
-            obj.Hix = kr(Hi_x,I_y);
-            obj.Hiy = kr(I_x,Hi_y);
-            obj.Hi = kr(Hi_x,Hi_y);
-
-            % Boundary operators
-            obj.e_w  = kr(e_l_x,I_y);
-            obj.e_e  = kr(e_r_x,I_y);
-            obj.e_s  = kr(I_x,e_l_y);
-            obj.e_n  = kr(I_x,e_r_y);
-            obj.d1_w = kr(d1_l_x,I_y);
-            obj.d1_e = kr(d1_r_x,I_y);
-            obj.d1_s = kr(I_x,d1_l_y);
-            obj.d1_n = kr(I_x,d1_r_y);
-            obj.d2_w = kr(d2_l_x,I_y);
-            obj.d2_e = kr(d2_r_x,I_y);
-            obj.d2_s = kr(I_x,d2_l_y);
-            obj.d2_n = kr(I_x,d2_r_y);
-            obj.d3_w = kr(d3_l_x,I_y);
-            obj.d3_e = kr(d3_r_x,I_y);
-            obj.d3_s = kr(I_x,d3_l_y);
-            obj.d3_n = kr(I_x,d3_r_y);
-
-            obj.D = alpha*D4;
-
-            obj.gamm_x = h_x*ops_x.borrowing.N.S2/2;
-            obj.delt_x = h_x^3*ops_x.borrowing.N.S3/2;
-
-            obj.gamm_y = h_y*ops_y.borrowing.N.S2/2;
-            obj.delt_y = h_y^3*ops_y.borrowing.N.S3/2;
-        end
-
-
-        % Closure functions return the opertors applied to the own doamin to close the boundary
-        % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
-        %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
-        %       type                is a string specifying the type of boundary condition if there are several.
-        %       data                is a function returning the data that should be applied at the boundary.
-        %       neighbour_scheme    is an instance of Scheme that should be interfaced to.
-        %       neighbour_boundary  is a string specifying which boundary to interface to.
-        function [closure, penalty_e,penalty_d] = boundary_condition(obj,boundary,type,data)
-            default_arg('type','dn');
-            default_arg('data',0);
-
-            [e,d1,d2,d3,s,gamm,delt,halfnorm_inv] = obj.get_boundary_ops(boundary);
-
-            switch type
-                % Dirichlet-neumann boundary condition
-                case {'dn'}
-                    alpha = obj.alpha;
-
-                    % tau1 < -alpha^2/gamma
-                    tuning = 1.1;
-
-                    tau1 = tuning * alpha/delt;
-                    tau4 = s*alpha;
-
-                    sig2 = tuning * alpha/gamm;
-                    sig3 = -s*alpha;
-
-                    tau = tau1*e+tau4*d3;
-                    sig = sig2*d1+sig3*d2;
-
-                    closure = halfnorm_inv*(tau*e' + sig*d1');
-
-                    pp_e = halfnorm_inv*tau;
-                    pp_d = halfnorm_inv*sig;
-                    switch class(data)
-                        case 'double'
-                            penalty_e = pp_e*data;
-                            penalty_d = pp_d*data;
-                        case 'function_handle'
-                            penalty_e = @(t)pp_e*data(t);
-                            penalty_d = @(t)pp_d*data(t);
-                        otherwise
-                            error('Wierd data argument!')
-                    end
-
-                % Unknown, boundary condition
-                otherwise
-                    error('No such boundary condition: type = %s',type);
-            end
-        end
-
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
-            % u denotes the solution in the own domain
-            % v denotes the solution in the neighbour domain
-            [e_u,d1_u,d2_u,d3_u,s_u,gamm_u,delt_u, halfnorm_inv] = obj.get_boundary_ops(boundary);
-            [e_v,d1_v,d2_v,d3_v,s_v,gamm_v,delt_v] = neighbour_scheme.get_boundary_ops(neighbour_boundary);
-
-            tuning = 2;
-
-            alpha_u = obj.alpha;
-            alpha_v = neighbour_scheme.alpha;
-
-            tau1 = ((alpha_u/2)/delt_u + (alpha_v/2)/delt_v)/2*tuning;
-            % tau1 = (alpha_u/2 + alpha_v/2)/(2*delt_u)*tuning;
-            tau4 = s_u*alpha_u/2;
-
-            sig2 = ((alpha_u/2)/gamm_u + (alpha_v/2)/gamm_v)/2*tuning;
-            sig3 = -s_u*alpha_u/2;
-
-            phi2 = s_u*1/2;
-
-            psi1 = -s_u*1/2;
-
-            tau = tau1*e_u  +                     tau4*d3_u;
-            sig =           sig2*d1_u + sig3*d2_u          ;
-            phi =           phi2*d1_u                      ;
-            psi = psi1*e_u                                 ;
-
-            closure =  halfnorm_inv*(tau*e_u' + sig*d1_u' + phi*alpha_u*d2_u' + psi*alpha_u*d3_u');
-            penalty = -halfnorm_inv*(tau*e_v' + sig*d1_v' + phi*alpha_v*d2_v' + psi*alpha_v*d3_v');
-        end
-
-        % Ruturns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
-        function [e,d1,d2,d3,s,gamm, delt, halfnorm_inv] = get_boundary_ops(obj,boundary)
-            switch boundary
-                case 'w'
-                    e  = obj.e_w;
-                    d1 = obj.d1_w;
-                    d2 = obj.d2_w;
-                    d3 = obj.d3_w;
-                    s = -1;
-                    gamm = obj.gamm_x;
-                    delt = obj.delt_x;
-                    halfnorm_inv = obj.Hix;
-                case 'e'
-                    e  = obj.e_e;
-                    d1 = obj.d1_e;
-                    d2 = obj.d2_e;
-                    d3 = obj.d3_e;
-                    s = 1;
-                    gamm = obj.gamm_x;
-                    delt = obj.delt_x;
-                    halfnorm_inv = obj.Hix;
-                case 's'
-                    e  = obj.e_s;
-                    d1 = obj.d1_s;
-                    d2 = obj.d2_s;
-                    d3 = obj.d3_s;
-                    s = -1;
-                    gamm = obj.gamm_y;
-                    delt = obj.delt_y;
-                    halfnorm_inv = obj.Hiy;
-                case 'n'
-                    e  = obj.e_n;
-                    d1 = obj.d1_n;
-                    d2 = obj.d2_n;
-                    d3 = obj.d3_n;
-                    s = 1;
-                    gamm = obj.gamm_y;
-                    delt = obj.delt_y;
-                    halfnorm_inv = obj.Hiy;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
-            end
-        end
-
-        function N = size(obj)
-            N = prod(obj.m);
-        end
-
-    end
-end
--- a/+scheme/Elastic2dCurvilinear.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Elastic2dCurvilinear.m	Tue Feb 12 17:12:42 2019 +0100
@@ -3,12 +3,12 @@
 % Discretizes the elastic wave equation in curvilinear coordinates.
 %
 % Untransformed equation:
-% rho u_{i,tt} = di lambda dj u_j + dj mu di u_j + dj mu dj u_i 
+% rho u_{i,tt} = di lambda dj u_j + dj mu di u_j + dj mu dj u_i
 %
 % Transformed equation:
-% J*rho u_{i,tt} = dk J b_ik lambda b_jl dl u_j 
-%                + dk J b_jk mu b_il dl u_j 
-%                + dk J b_jk mu b_jl dl u_i 
+% J*rho u_{i,tt} = dk J b_ik lambda b_jl dl u_j
+%                + dk J b_jk mu b_il dl u_j
+%                + dk J b_jk mu b_jl dl u_i
 % opSet should be cell array of opSets, one per dimension. This
 % is useful if we have periodic BC in one direction.
 
@@ -49,7 +49,7 @@
         e_l, e_r
         d1_l, d1_r % Normal derivatives at the boundary
         E % E{i}^T picks out component i
-        
+
         H_boundary_l, H_boundary_r % Boundary inner products
 
         % Kroneckered norms and coefficients
@@ -145,7 +145,7 @@
             opSetMetric{1} = sbp.D2Variable(m(1), {0, xmax}, order);
             opSetMetric{2} = sbp.D2Variable(m(2), {0, ymax}, order);
             D1Metric{1} = kron(opSetMetric{1}.D1, I{2});
-            D1Metric{2} = kron(I{1}, opSetMetric{2}.D1); 
+            D1Metric{2} = kron(I{1}, opSetMetric{2}.D1);
 
             x_xi = D1Metric{1}*x;
             x_eta = D1Metric{2}*x;
@@ -327,12 +327,12 @@
 
                         for m = 1:dim
                             for l = 1:dim
-                                T_l{j}{i,k} = T_l{j}{i,k} + ... 
+                                T_l{j}{i,k} = T_l{j}{i,k} + ...
                                 -d(k,l)* J*b{i,j}*b{k,m}*LAMBDA*(d(m,j)*e_l{m}*d1_l{m}' + db(m,j)*D1{m}) ...
                                 -d(k,l)* J*b{k,j}*b{i,m}*MU*(d(m,j)*e_l{m}*d1_l{m}' + db(m,j)*D1{m}) ...
                                 -d(i,k)* J*b{l,j}*b{l,m}*MU*(d(m,j)*e_l{m}*d1_l{m}' + db(m,j)*D1{m});
 
-                                T_r{j}{i,k} = T_r{j}{i,k} + ... 
+                                T_r{j}{i,k} = T_r{j}{i,k} + ...
                                 d(k,l)* J*b{i,j}*b{k,m}*LAMBDA*(d(m,j)*e_r{m}*d1_r{m}' + db(m,j)*D1{m}) + ...
                                 d(k,l)* J*b{k,j}*b{i,m}*MU*(d(m,j)*e_r{m}*d1_r{m}' + db(m,j)*D1{m}) + ...
                                 d(i,k)* J*b{l,j}*b{l,m}*MU*(d(m,j)*e_r{m}*d1_r{m}' + db(m,j)*D1{m});
@@ -340,7 +340,7 @@
                         end
 
                         T_l{j}{i,k} = inv(beta{j})*T_l{j}{i,k};
-                        T_r{j}{i,k} = inv(beta{j})*T_r{j}{i,k}; 
+                        T_r{j}{i,k} = inv(beta{j})*T_r{j}{i,k};
 
                         tau_l{j}{i} = tau_l{j}{i} + T_l{j}{i,k}*E{k}';
                         tau_r{j}{i} = tau_r{j}{i} + T_r{j}{i,k}*E{k}';
@@ -387,7 +387,7 @@
 
             % j is the coordinate direction of the boundary
             j = obj.get_boundary_number(boundary);
-            [e, T, tau, H_gamma] = obj.get_boundary_operator({'e','T','tau','H'}, boundary);
+            [e, T, tau, H_gamma] = obj.getBoundaryOperator({'e','T','tau','H'}, boundary);
 
             E = obj.E;
             Hi = obj.Hi;
@@ -423,20 +423,20 @@
                 db = @(i,j) 1-d(i,j); % Logical not of Kronecker delta
                 alpha = @(i,j) tuning*( d(i,j)* a_lambda*LAMBDA ...
                                       + d(i,j)* a_mu_i*MU ...
-                                      + db(i,j)*a_mu_ij*MU ); 
+                                      + db(i,j)*a_mu_ij*MU );
 
                 % Loop over components that Dirichlet penalties end up on
                 for i = 1:dim
                     C = T{k,i};
                     A = -d(i,k)*alpha(i,j);
                     B = A + C;
-                    closure = closure + E{i}*RHOi*Hi*Ji*B'*e*H_gamma*(e'*E{k}' ); 
+                    closure = closure + E{i}*RHOi*Hi*Ji*B'*e*H_gamma*(e'*E{k}' );
                     penalty = penalty - E{i}*RHOi*Hi*Ji*B'*e*H_gamma;
-                end 
+                end
 
             % Free boundary condition
             case {'F','f','Free','free','traction','Traction','t','T'}
-                    closure = closure - E{k}*RHOi*Ji*Hi*e*H_gamma* (e'*tau{k} ); 
+                    closure = closure - E{k}*RHOi*Ji*Hi*e*H_gamma* (e'*tau{k} );
                     penalty = penalty + E{k}*RHOi*Ji*Hi*e*H_gamma;
 
             % Unknown boundary condition
@@ -457,14 +457,14 @@
             j_v = neighbour_scheme.get_boundary_number(neighbour_boundary);
 
             % Get boundary operators
-            [e, T, tau, H_gamma] = obj.get_boundary_operator({'e','T','tau','H'}, boundary);
-            [e_v, tau_v] = neighbour_scheme.get_boundary_operator({'e','tau'}, neighbour_boundary);
+            [e, T, tau, H_gamma] = obj.getBoundaryOperator({'e','T','tau','H'}, boundary);
+            [e_v, tau_v] = neighbour_scheme.getBoundaryOperator({'e','tau'}, neighbour_boundary);
 
             % Operators and quantities that correspond to the own domain only
             Hi = obj.Hi;
             RHOi = obj.RHOi;
             dim = obj.dim;
-        
+
             %--- Other operators ----
             m_tot_u = obj.grid.N();
             E = obj.E;
@@ -480,7 +480,7 @@
             lambda_v = e_v'*LAMBDA_v*e_v;
             mu_v = e_v'*MU_v*e_v;
             %-------------------------
-            
+
             % Borrowing constants
             phi_u = obj.phi{j};
             h_u = obj.h(j);
@@ -493,7 +493,7 @@
             gamma_v = neighbour_scheme.gamma{j_v};
 
             % E > sum_i 1/(2*alpha_ij)*(tau_i)^2
-            function [alpha_ii, alpha_ij] = computeAlpha(phi,h,h11,gamma,lambda,mu) 
+            function [alpha_ii, alpha_ij] = computeAlpha(phi,h,h11,gamma,lambda,mu)
                 th1 = h11/(2*dim);
                 th2 = h11*phi/2;
                 th3 = h*gamma;
@@ -505,7 +505,7 @@
             end
 
             [alpha_ii_u, alpha_ij_u] = computeAlpha(phi_u,h_u,h11_u,gamma_u,lambda_u,mu_u);
-            [alpha_ii_v, alpha_ij_v] = computeAlpha(phi_v,h_v,h11_v,gamma_v,lambda_v,mu_v);  
+            [alpha_ii_v, alpha_ij_v] = computeAlpha(phi_v,h_v,h11_v,gamma_v,lambda_v,mu_v);
             sigma_ii = tuning*(alpha_ii_u + alpha_ii_v)/4;
             sigma_ij = tuning*(alpha_ij_u + alpha_ij_v)/4;
 
@@ -527,9 +527,9 @@
 
                 % Loop over components that we have interface conditions on
                 for k = 1:dim
-                    closure = closure + 1/2*E{i}*RHOi*Hi*T{k,i}'*e*H_gamma*e'*E{k}'; 
-                    penalty = penalty - 1/2*E{i}*RHOi*Hi*T{k,i}'*e*H_gamma*e_v'*E_v{k}'; 
-                end 
+                    closure = closure + 1/2*E{i}*RHOi*Hi*T{k,i}'*e*H_gamma*e'*E{k}';
+                    penalty = penalty - 1/2*E{i}*RHOi*Hi*T{k,i}'*e*H_gamma*e_v'*E_v{k}';
+                end
             end
         end
 
@@ -555,7 +555,7 @@
 
         % Returns the boundary operator op for the boundary specified by the string boundary.
         % op: may be a cell array of strings
-        function [varargout] = get_boundary_operator(obj, op, boundary)
+        function [varargout] = getBoundaryOperator(obj, op, boundary)
 
             switch boundary
                 case {'w','W','west','West', 'e', 'E', 'east', 'East'}
@@ -587,7 +587,7 @@
                                 varargout{i} = obj.d1_r{j};
                         end
                     case 'H'
-                        switch boundary 
+                        switch boundary
                             case {'w','W','west','West','s','S','south','South'}
                                     varargout{i} = obj.H_boundary_l{j};
                             case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
@@ -606,7 +606,7 @@
                                 varargout{i} = obj.tau_l{j};
                             case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
                                 varargout{i} = obj.tau_r{j};
-                        end                        
+                        end
                     otherwise
                         error(['No such operator: operator = ' op{i}]);
                 end
@@ -614,6 +614,27 @@
 
         end
 
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'w'}
+                    H = H_boundary_l{1};
+                case 'e'
+                    H = H_boundary_r{1};
+                case 's'
+                    H = H_boundary_l{2};
+                case 'n'
+                    H = H_boundary_r{2};
+            end
+            I_dim = speye(obj.dim, obj.dim);
+            H = kron(H, I_dim);
+        end
+
         function N = size(obj)
             N = obj.dim*prod(obj.m);
         end
--- a/+scheme/Elastic2dVariable.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Elastic2dVariable.m	Tue Feb 12 17:12:42 2019 +0100
@@ -30,18 +30,10 @@
         T_l, T_r
         tau_l, tau_r
 
-        H, Hi % Inner products
-
-        phi % Borrowing constant for (d1 - e^T*D1) from R
-        gamma % Borrowing constant for d1 from M
-        H11 % First element of H
+        H, Hi, H_1D % Inner products
+        e_l, e_r
 
-        % Borrowing from H, M, and R
-        thH
-        thM
-        thR
 
-        e_l, e_r
         d1_l, d1_r % Normal derivatives at the boundary
         E % E{i}^T picks out component i
 
@@ -50,22 +42,38 @@
         % Kroneckered norms and coefficients
         RHOi_kron
         Hi_kron
+
+        % Borrowing constants of the form gamma*h, where gamma is a dimensionless constant.
+        theta_R % Borrowing (d1- D1)^2 from R
+        theta_H % First entry in norm matrix
+        theta_M % Borrowing d1^2 from M.
+
+        % Structures used for adjoint optimization
+        B
     end
 
     methods
 
-        function obj = Elastic2dVariable(g ,order, lambda_fun, mu_fun, rho_fun, opSet)
+        % The coefficients can either be function handles or grid functions
+        function obj = Elastic2dVariable(g ,order, lambda, mu, rho, opSet)
             default_arg('opSet',{@sbp.D2Variable, @sbp.D2Variable});
-            default_arg('lambda_fun', @(x,y) 0*x+1);
-            default_arg('mu_fun', @(x,y) 0*x+1);
-            default_arg('rho_fun', @(x,y) 0*x+1);
+            default_arg('lambda', @(x,y) 0*x+1);
+            default_arg('mu', @(x,y) 0*x+1);
+            default_arg('rho', @(x,y) 0*x+1);
             dim = 2;
 
             assert(isa(g, 'grid.Cartesian'))
 
-            lambda = grid.evalOn(g, lambda_fun);
-            mu = grid.evalOn(g, mu_fun);
-            rho = grid.evalOn(g, rho_fun);
+            if isa(lambda, 'function_handle')
+                lambda = grid.evalOn(g, lambda);
+            end
+            if isa(mu, 'function_handle')
+                mu = grid.evalOn(g, mu);
+            end
+            if isa(rho, 'function_handle')
+                rho = grid.evalOn(g, rho);
+            end
+
             m = g.size();
             m_tot = g.N();
 
@@ -87,15 +95,9 @@
 
             % Borrowing constants
             for i = 1:dim
-                beta = ops{i}.borrowing.R.delta_D;
-                obj.H11{i} = ops{i}.borrowing.H11;
-                obj.phi{i} = beta/obj.H11{i};
-                obj.gamma{i} = ops{i}.borrowing.M.d1;
-
-                % Better names
-                obj.thR{i} = ops{i}.borrowing.R.delta_D;
-                obj.thM{i} = ops{i}.borrowing.M.d1;
-                obj.thH{i} = ops{i}.borrowing.H11;
+                obj.theta_R{i} = h(i)*ops{i}.borrowing.R.delta_D;
+                obj.theta_H{i} = h(i)*ops{i}.borrowing.H11;
+                obj.theta_M{i} = h(i)*ops{i}.borrowing.M.d1;
             end
 
             I = cell(dim,1);
@@ -183,6 +185,7 @@
             obj.H_boundary = cell(dim,1);
             obj.H_boundary{1} = H{2};
             obj.H_boundary{2} = H{1};
+            obj.H_1D = {H{1}, H{2}};
 
             % E{i}^T picks out component i.
             E = cell(dim,1);
@@ -213,7 +216,7 @@
                 end
             end
             obj.D = D;
-            %=========================================%
+            %=========================================%'
 
             % Numerical traction operators for BC.
             % Because d1 =/= e0^T*D1, the numerical tractions are different
@@ -237,20 +240,28 @@
                 tau_l{j} = cell(dim,1);
                 tau_r{j} = cell(dim,1);
 
+                LAMBDA_l = e_l{j}'*LAMBDA*e_l{j};
+                LAMBDA_r = e_r{j}'*LAMBDA*e_r{j};
+                MU_l = e_l{j}'*MU*e_l{j};
+                MU_r = e_r{j}'*MU*e_r{j};
+
+                [~, n_l] = size(e_l{j});
+                [~, n_r] = size(e_r{j});
+
                 % Loop over components
                 for i = 1:dim
-                    tau_l{j}{i} = sparse(m_tot,dim*m_tot);
-                    tau_r{j}{i} = sparse(m_tot,dim*m_tot);
+                    tau_l{j}{i} = sparse(n_l, dim*m_tot);
+                    tau_r{j}{i} = sparse(n_r, dim*m_tot);
                     for k = 1:dim
                         T_l{j}{i,k} = ...
-                        -d(i,j)*LAMBDA*(d(i,k)*e_l{k}*d1_l{k}' + db(i,k)*D1{k})...
-                        -d(j,k)*MU*(d(i,j)*e_l{i}*d1_l{i}' + db(i,j)*D1{i})...
-                        -d(i,k)*MU*e_l{j}*d1_l{j}';
+                        -d(i,j)*LAMBDA_l*(d(i,k)*d1_l{j}' + db(i,k)*e_l{j}'*D1{k})...
+                        -d(j,k)*MU_l*(d(i,j)*d1_l{j}' + db(i,j)*e_l{j}'*D1{i})...
+                        -d(i,k)*MU_l*d1_l{j}';
 
                         T_r{j}{i,k} = ...
-                        d(i,j)*LAMBDA*(d(i,k)*e_r{k}*d1_r{k}' + db(i,k)*D1{k})...
-                        +d(j,k)*MU*(d(i,j)*e_r{i}*d1_r{i}' + db(i,j)*D1{i})...
-                        +d(i,k)*MU*e_r{j}*d1_r{j}';
+                        d(i,j)*LAMBDA_r*(d(i,k)*d1_r{j}' + db(i,k)*e_r{j}'*D1{k})...
+                        +d(j,k)*MU_r*(d(i,j)*d1_r{j}' + db(i,j)*e_r{j}'*D1{i})...
+                        +d(i,k)*MU_r*d1_r{j}';
 
                         tau_l{j}{i} = tau_l{j}{i} + T_l{j}{i,k}*E{k}';
                         tau_r{j}{i} = tau_r{j}{i} + T_r{j}{i,k}*E{k}';
@@ -258,6 +269,19 @@
 
                 end
             end
+
+            % Transpose T and tau to match boundary operator convention
+            for i = 1:dim
+                for j = 1:dim
+                    tau_l{i}{j} = transpose(tau_l{i}{j});
+                    tau_r{i}{j} = transpose(tau_r{i}{j});
+                    for k = 1:dim
+                        T_l{i}{j,k} = transpose(T_l{i}{j,k});
+                        T_r{i}{j,k} = transpose(T_r{i}{j,k});
+                    end
+                end
+            end
+
             obj.T_l = T_l;
             obj.T_r = T_r;
             obj.tau_l = tau_l;
@@ -275,6 +299,44 @@
             obj.grid = g;
             obj.dim = dim;
 
+            % B, used for adjoint optimization
+            B = cell(dim, 1);
+            for i = 1:dim
+                B{i} = cell(m_tot, 1);
+            end
+
+            for i = 1:dim
+                for j = 1:m_tot
+                    B{i}{j} = sparse(m_tot, m_tot);
+                end
+            end
+
+            ind = grid.funcToMatrix(g, 1:m_tot);
+
+            % Direction 1
+            for k = 1:m(1)
+                c = sparse(m(1),1);
+                c(k) = 1;
+                [~, B_1D] = ops{1}.D2(c);
+                for l = 1:m(2)
+                    p = ind(:,l);
+                    B{1}{(k-1)*m(2) + l}(p, p) = B_1D;
+                end
+            end
+
+            % Direction 2
+            for k = 1:m(2)
+                c = sparse(m(2),1);
+                c(k) = 1;
+                [~, B_1D] = ops{2}.D2(c);
+                for l = 1:m(1)
+                    p = ind(l,:);
+                    B{2}{(l-1)*m(2) + k}(p, p) = B_1D;
+                end
+            end
+
+            obj.B = B;
+
         end
 
 
@@ -295,7 +357,8 @@
 
             % j is the coordinate direction of the boundary
             j = obj.get_boundary_number(boundary);
-            [e, T, tau, H_gamma] = obj.get_boundary_operator({'e','T','tau','H'}, boundary);
+            [e, T, tau, H_gamma] = obj.getBoundaryOperator({'e','T','tau','H'}, boundary);
+
 
             E = obj.E;
             Hi = obj.Hi;
@@ -316,33 +379,20 @@
             % Dirichlet boundary condition
             case {'D','d','dirichlet','Dirichlet'}
 
-                phi = obj.phi{j};
-                h = obj.h(j);
-                h11 = obj.H11{j}*h;
-                gamma = obj.gamma{j};
-
-                a_lambda = dim/h11 + 1/(h11*phi);
-                a_mu_i = 2/(gamma*h);
-                a_mu_ij = 2/h11 + 1/(h11*phi);
-
-                d = @kroneckerDelta;  % Kronecker delta
-                db = @(i,j) 1-d(i,j); % Logical not of Kronecker delta
-                alpha = @(i,j) tuning*( d(i,j)* a_lambda*LAMBDA ...
-                                      + d(i,j)* a_mu_i*MU ...
-                                      + db(i,j)*a_mu_ij*MU );
+                alpha = obj.getBoundaryOperator('alpha', boundary);
 
                 % Loop over components that Dirichlet penalties end up on
                 for i = 1:dim
-                    C = T{k,i};
-                    A = -d(i,k)*alpha(i,j);
-                    B = A + C;
+                    C = transpose(T{k,i});
+                    A = -tuning*e*transpose(alpha{i,k});
+                    B = A + e*C;
                     closure = closure + E{i}*RHOi*Hi*B'*e*H_gamma*(e'*E{k}' );
                     penalty = penalty - E{i}*RHOi*Hi*B'*e*H_gamma;
                 end
 
             % Free boundary condition
             case {'F','f','Free','free','traction','Traction','t','T'}
-                    closure = closure - E{k}*RHOi*Hi*e*H_gamma* (e'*tau{k} );
+                    closure = closure - E{k}*RHOi*Hi*e*H_gamma*tau{k}';
                     penalty = penalty + E{k}*RHOi*Hi*e*H_gamma;
 
             % Unknown boundary condition
@@ -351,160 +401,216 @@
             end
         end
 
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
+        % type     Struct that specifies the interface coupling.
+        %          Fields:
+        %          -- tuning:           penalty strength, defaults to 1.2
+        %          -- interpolation:    type of interpolation, default 'none'
+        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+            defaultType.tuning = 1.2;
+            defaultType.interpolation = 'none';
+            default_struct('type', defaultType);
+
+            switch type.interpolation
+            case {'none', ''}
+                [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            case {'op','OP'}
+                [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            otherwise
+                error('Unknown type of interpolation: %s ', type.interpolation);
+            end
+        end
+
+        function [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+            tuning = type.tuning;
+
             % u denotes the solution in the own domain
             % v denotes the solution in the neighbour domain
             % Operators without subscripts are from the own domain.
-            tuning = 1.2;
-
-            % j is the coordinate direction of the boundary
-            j = obj.get_boundary_number(boundary);
-            j_v = neighbour_scheme.get_boundary_number(neighbour_boundary);
 
             % Get boundary operators
-            [e, T, tau, H_gamma] = obj.get_boundary_operator({'e','T','tau','H'}, boundary);
-            [e_v, tau_v] = neighbour_scheme.get_boundary_operator({'e','tau'}, neighbour_boundary);
+            e = obj.getBoundaryOperator('e_tot', boundary);
+            tau = obj.getBoundaryOperator('tau_tot', boundary);
+
+            e_v = neighbour_scheme.getBoundaryOperator('e_tot', neighbour_boundary);
+            tau_v = neighbour_scheme.getBoundaryOperator('tau_tot', neighbour_boundary);
+
+            H_gamma = obj.getBoundaryQuadrature(boundary);
 
             % Operators and quantities that correspond to the own domain only
-            Hi = obj.Hi;
-            RHOi = obj.RHOi;
-            dim = obj.dim;
-
-            %--- Other operators ----
-            m_tot_u = obj.grid.N();
-            E = obj.E;
-            LAMBDA_u = obj.LAMBDA;
-            MU_u = obj.MU;
-            lambda_u = e'*LAMBDA_u*e;
-            mu_u = e'*MU_u*e;
+            Hi = obj.Hi_kron;
+            RHOi = obj.RHOi_kron;
 
-            m_tot_v = neighbour_scheme.grid.N();
-            E_v = neighbour_scheme.E;
-            LAMBDA_v = neighbour_scheme.LAMBDA;
-            MU_v = neighbour_scheme.MU;
-            lambda_v = e_v'*LAMBDA_v*e_v;
-            mu_v = e_v'*MU_v*e_v;
-            %-------------------------
+            % Penalty strength operators
+            alpha_u = 1/4*tuning*obj.getBoundaryOperator('alpha_tot', boundary);
+            alpha_v = 1/4*tuning*neighbour_scheme.getBoundaryOperator('alpha_tot', neighbour_boundary);
 
-            % Borrowing constants
-            h_u = obj.h(j);
-            thR_u = obj.thR{j}*h_u;
-            thM_u = obj.thM{j}*h_u;
-            thH_u = obj.thH{j}*h_u;
-
-            h_v = neighbour_scheme.h(j_v);
-            thR_v = neighbour_scheme.thR{j_v}*h_v;
-            thH_v = neighbour_scheme.thH{j_v}*h_v;
-            thM_v = neighbour_scheme.thM{j_v}*h_v;
+            closure = -RHOi*Hi*e*H_gamma*(alpha_u' + alpha_v'*e_v*e');
+            penalty = RHOi*Hi*e*H_gamma*(alpha_u'*e*e_v' + alpha_v');
 
-            % alpha = penalty strength for normal component, beta for tangential
-            alpha_u = dim*lambda_u/(4*thH_u) + lambda_u/(4*thR_u) + mu_u/(2*thM_u);
-            alpha_v = dim*lambda_v/(4*thH_v) + lambda_v/(4*thR_v) + mu_v/(2*thM_v);
-            beta_u = mu_u/(2*thH_u) + mu_u/(4*thR_u);
-            beta_v = mu_v/(2*thH_v) + mu_v/(4*thR_v);
-            alpha = alpha_u + alpha_v;
-            beta = beta_u + beta_v;
-
-            d = @kroneckerDelta;  % Kronecker delta
-            db = @(i,j) 1-d(i,j); % Logical not of Kronecker delta
-            strength = @(i,j) tuning*(d(i,j)*alpha + db(i,j)*beta);
+            closure = closure - 1/2*RHOi*Hi*e*H_gamma*tau';
+            penalty = penalty - 1/2*RHOi*Hi*e*H_gamma*tau_v';
 
-            % Preallocate
-            closure = sparse(dim*m_tot_u, dim*m_tot_u);
-            penalty = sparse(dim*m_tot_u, dim*m_tot_v);
-
-            % Loop over components that penalties end up on
-            for i = 1:dim
-                closure = closure - E{i}*RHOi*Hi*e*strength(i,j)*H_gamma*e'*E{i}';
-                penalty = penalty + E{i}*RHOi*Hi*e*strength(i,j)*H_gamma*e_v'*E_v{i}';
+            closure = closure + 1/2*RHOi*Hi*tau*H_gamma*e';
+            penalty = penalty - 1/2*RHOi*Hi*tau*H_gamma*e_v';
 
-                closure = closure - 1/2*E{i}*RHOi*Hi*e*H_gamma*e'*tau{i};
-                penalty = penalty - 1/2*E{i}*RHOi*Hi*e*H_gamma*e_v'*tau_v{i};
+        end
 
-                % Loop over components that we have interface conditions on
-                for k = 1:dim
-                    closure = closure + 1/2*E{i}*RHOi*Hi*T{k,i}'*e*H_gamma*e'*E{k}';
-                    penalty = penalty - 1/2*E{i}*RHOi*Hi*T{k,i}'*e*H_gamma*e_v'*E_v{k}';
-                end
-            end
+        function [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+            error('Non-conforming interfaces not implemented yet.');
         end
 
         % Returns the coordinate number and outward normal component for the boundary specified by the string boundary.
         function [j, nj] = get_boundary_number(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
             switch boundary
-                case {'w','W','west','West', 'e', 'E', 'east', 'East'}
+                case {'w', 'e'}
                     j = 1;
-                case {'s','S','south','South', 'n', 'N', 'north', 'North'}
+                case {'s', 'n'}
                     j = 2;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
             end
 
             switch boundary
-                case {'w','W','west','West','s','S','south','South'}
+                case {'w', 's'}
                     nj = -1;
-                case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
+                case {'e', 'n'}
                     nj = 1;
             end
         end
 
         % Returns the boundary operator op for the boundary specified by the string boundary.
-        % op: may be a cell array of strings
-        function [varargout] = get_boundary_operator(obj, op, boundary)
+        % op -- string
+        % Only operators with name *_tot can be used with multiblock.DiffOp.getBoundaryOperator()
+        function [varargout] = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+            assertIsMember(op, {'e', 'e_tot', 'd', 'T', 'tau', 'tau_tot', 'H', 'alpha', 'alpha_tot'})
 
             switch boundary
-                case {'w','W','west','West', 'e', 'E', 'east', 'East'}
+                case {'w', 'e'}
                     j = 1;
-                case {'s','S','south','South', 'n', 'N', 'north', 'North'}
+                case {'s', 'n'}
                     j = 2;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
-            end
-
-            if ~iscell(op)
-                op = {op};
             end
 
-            for i = 1:length(op)
-                switch op{i}
-                    case 'e'
-                        switch boundary
-                            case {'w','W','west','West','s','S','south','South'}
-                                varargout{i} = obj.e_l{j};
-                            case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                                varargout{i} = obj.e_r{j};
-                        end
-                    case 'd'
-                        switch boundary
-                            case {'w','W','west','West','s','S','south','South'}
-                                varargout{i} = obj.d1_l{j};
-                            case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                                varargout{i} = obj.d1_r{j};
+            switch op
+                case 'e'
+                    switch boundary
+                        case {'w', 's'}
+                            o = obj.e_l{j};
+                        case {'e', 'n'}
+                            o = obj.e_r{j};
+                    end
+
+                case 'e_tot'
+                    e = obj.getBoundaryOperator('e', boundary);
+                    I_dim = speye(obj.dim, obj.dim);
+                    o = kron(e, I_dim);
+
+                case 'd'
+                    switch boundary
+                        case {'w', 's'}
+                            o = obj.d1_l{j};
+                        case {'e', 'n'}
+                            o = obj.d1_r{j};
+                    end
+
+                case 'T'
+                    switch boundary
+                        case {'w', 's'}
+                            o = obj.T_l{j};
+                        case {'e', 'n'}
+                            o = obj.T_r{j};
+                    end
+
+                case 'tau'
+                    switch boundary
+                        case {'w', 's'}
+                            o = obj.tau_l{j};
+                        case {'e', 'n'}
+                            o = obj.tau_r{j};
+                    end
+
+                case 'tau_tot'
+                    [e, tau] = obj.getBoundaryOperator({'e', 'tau'}, boundary);
+
+                    I_dim = speye(obj.dim, obj.dim);
+                    e_tot = kron(e, I_dim);
+                    E = obj.E;
+                    tau_tot = (e_tot'*E{1}*e*tau{1}')';
+                    for i = 2:obj.dim
+                        tau_tot = tau_tot + (e_tot'*E{i}*e*tau{i}')';
+                    end
+                    o = tau_tot;
+
+                case 'H'
+                    o = obj.H_boundary{j};
+
+                case 'alpha'
+                    % alpha = alpha(i,j) is the penalty strength for displacement BC.
+                    e = obj.getBoundaryOperator('e', boundary);
+
+                    LAMBDA = obj.LAMBDA;
+                    MU = obj.MU;
+
+                    dim = obj.dim;
+                    theta_R = obj.theta_R{j};
+                    theta_H = obj.theta_H{j};
+                    theta_M = obj.theta_M{j};
+
+                    a_lambda = dim/theta_H + 1/theta_R;
+                    a_mu_i = 2/theta_M;
+                    a_mu_ij = 2/theta_H + 1/theta_R;
+
+                    d = @kroneckerDelta;  % Kronecker delta
+                    db = @(i,j) 1-d(i,j); % Logical not of Kronecker delta
+                    alpha = cell(obj.dim, obj.dim);
+
+                    alpha_func = @(i,j) d(i,j)* a_lambda*LAMBDA ...
+                                        + d(i,j)* a_mu_i*MU ...
+                                        + db(i,j)*a_mu_ij*MU;
+                    for i = 1:obj.dim
+                        for l = 1:obj.dim
+                            alpha{i,l} = d(i,l)*alpha_func(i,j)*e;
                         end
-                    case 'H'
-                        varargout{i} = obj.H_boundary{j};
-                    case 'T'
-                        switch boundary
-                            case {'w','W','west','West','s','S','south','South'}
-                                varargout{i} = obj.T_l{j};
-                            case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                                varargout{i} = obj.T_r{j};
+                    end
+
+                    o = alpha;
+
+                case 'alpha_tot'
+                    % alpha = alpha(i,j) is the penalty strength for displacement BC.
+                    [e, e_tot, alpha] = obj.getBoundaryOperator({'e', 'e_tot', 'alpha'}, boundary);
+                    E = obj.E;
+                    [m, n] = size(alpha{1,1});
+                    alpha_tot = sparse(m*obj.dim, n*obj.dim);
+                    for i = 1:obj.dim
+                        for l = 1:obj.dim
+                            alpha_tot = alpha_tot + (e_tot'*E{i}*e*alpha{i,l}'*E{l}')';
                         end
-                    case 'tau'
-                        switch boundary
-                            case {'w','W','west','West','s','S','south','South'}
-                                varargout{i} = obj.tau_l{j};
-                            case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                                varargout{i} = obj.tau_r{j};
-                        end
-                    otherwise
-                        error(['No such operator: operator = ' op{i}]);
-                end
+                    end
+                    o = alpha_tot;
             end
 
         end
 
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'w','e'}
+                    j = 1;
+                case {'s','n'}
+                    j = 2;
+            end
+            H = obj.H_boundary{j};
+            I_dim = speye(obj.dim, obj.dim);
+            H = kron(H, I_dim);
+        end
+
         function N = size(obj)
             N = obj.dim*prod(obj.m);
         end
--- a/+scheme/Euler1d.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Euler1d.m	Tue Feb 12 17:12:42 2019 +0100
@@ -201,7 +201,8 @@
         % Enforces the boundary conditions
         %  w+ = R*w- + g(t)
         function closure = boundary_condition(obj,boundary, type, varargin)
-            [e_s,e_S,s] = obj.get_boundary_ops(boundary);
+            [e_s, e_S] = obj.getBoundaryOperator({'e', 'E'}, boundary);
+            s = obj.getBoundarySign(boundary);
 
             % Boundary condition on form
             %   w_in = R*w_out + g,       where g is data
@@ -232,7 +233,8 @@
         %
         % Returns closure(q,g)
         function closure = boundary_condition_L(obj, boundary, L_fun, p_in)
-            [e_s,e_S,s] = obj.get_boundary_ops(boundary);
+            [e_s, e_S] = obj.getBoundaryOperator({'e', 'E'}, boundary);
+            s = obj.getBoundarySign(boundary);
 
             p_ot = 1:3;
             p_ot(p_in) = [];
@@ -273,7 +275,8 @@
 
         % Return closure(q,g)
         function closure = boundary_condition_char(obj,boundary)
-            [e_s,e_S,s] = obj.get_boundary_ops(boundary);
+            [e_s, e_S] = obj.getBoundaryOperator({'e', 'E'}, boundary);
+            s = obj.getBoundarySign(boundary);
 
             function o = closure_fun(q, w_data)
                 q_s = e_S'*q;
@@ -314,7 +317,7 @@
 
         % Return closure(q,[v; p])
         function closure = boundary_condition_inflow(obj, boundary)
-            [~,~,s] = obj.get_boundary_ops(boundary);
+            s = obj.getBoundarySign(boundary);
 
              switch s
                 case -1
@@ -335,7 +338,7 @@
 
         % Return closure(q, p)
         function closure = boundary_condition_outflow(obj, boundary)
-            [~,~,s] = obj.get_boundary_ops(boundary);
+            s = obj.getBoundarySign(boundary);
 
              switch s
                 case -1
@@ -352,7 +355,7 @@
 
         % Return closure(q,[v; rho])
         function closure = boundary_condition_inflow_rho(obj, boundary)
-            [~,~,s] = obj.get_boundary_ops(boundary);
+            s = obj.getBoundarySign(boundary);
 
              switch s
                 case -1
@@ -372,7 +375,7 @@
 
         % Return closure(q,rho)
         function closure = boundary_condition_outflow_rho(obj, boundary)
-            [~,~,s] = obj.get_boundary_ops(boundary);
+            s = obj.getBoundarySign(boundary);
 
              switch s
                 case -1
@@ -388,7 +391,8 @@
 
         % Set wall boundary condition v = 0.
         function closure = boundary_condition_wall(obj,boundary)
-            [e_s,e_S,s] = obj.get_boundary_ops(boundary);
+            [e_s, e_S] = obj.getBoundaryOperator({'e', 'E'}, boundary);
+            s = obj.getBoundarySign(boundary);
 
             % Vill vi sätta penalty på karateristikan som är nära noll också eller vill
             % vi låta den vara fri?
@@ -446,7 +450,7 @@
             closure = @closure_fun;
         end
 
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
             error('NOT DONE')
             % u denotes the solution in the own domain
             % v denotes the solution in the neighbour domain
@@ -478,18 +482,61 @@
             penalty = -halfnorm_inv*(tau*e_v' + sig*d1_v' + phi*alpha_v*d2_v' + psi*alpha_v*d3_v');
         end
 
-        % Ruturns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
-        function [e,E,s] = get_boundary_ops(obj,boundary)
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+
+            if ~iscell(op)
+                op = {op};
+            end
+
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'l'
+                        e = obj.e_l;
+                    case 'r'
+                        e = obj.e_r;
+                    otherwise
+                        error('No such boundary: boundary = %s',boundary);
+                    end
+                    varargout{i} = e;
+
+                case 'E'
+                    switch boundary
+                    case 'l'
+                        E = obj.e_L;
+                    case 'r'
+                        E = obj.e_R;
+                    otherwise
+                        error('No such boundary: boundary = %s',boundary);
+                    end
+                    varargout{i} = E;
+                end
+            end
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        % Note: for 1d diffOps, the boundary quadrature is the scalar 1.
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
+            H_b = 1;
+        end
+
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
             switch boundary
-                case 'l'
-                    e  = obj.e_l;
-                    E  = obj.e_L;
+                case {'r'}
+                    s = 1;
+                case {'l'}
                     s = -1;
-                case 'r'
-                    e  = obj.e_r;
-                    E  = obj.e_R;
-                    s = 1;
                 otherwise
                     error('No such boundary: boundary = %s',boundary);
             end
--- a/+scheme/Heat2dCurvilinear.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Heat2dCurvilinear.m	Tue Feb 12 17:12:42 2019 +0100
@@ -1,9 +1,9 @@
 classdef Heat2dCurvilinear < scheme.Scheme
 
 % Discretizes the Laplacian with variable coefficent, curvilinear,
-% in the Heat equation way (i.e., the discretization matrix is not necessarily 
+% in the Heat equation way (i.e., the discretization matrix is not necessarily
 % symmetric)
-% u_t = div * (kappa * grad u ) 
+% u_t = div * (kappa * grad u )
 % opSet should be cell array of opSets, one per dimension. This
 % is useful if we have periodic BC in one direction.
 
@@ -29,9 +29,9 @@
         e_l, e_r
         d1_l, d1_r % Normal derivatives at the boundary
         alpha % Vector of borrowing constants
-        
+
         % Boundary inner products
-        H_boundary_l, H_boundary_r 
+        H_boundary_l, H_boundary_r
 
         % Metric coefficients
         b % Cell matrix of size dim x dim
@@ -109,7 +109,7 @@
             opSetMetric{1} = sbp.D2Variable(m(1), {0, xmax}, order);
             opSetMetric{2} = sbp.D2Variable(m(2), {0, ymax}, order);
             D1Metric{1} = kron(opSetMetric{1}.D1, I{2});
-            D1Metric{2} = kron(I{1}, opSetMetric{2}.D1); 
+            D1Metric{2} = kron(I{1}, opSetMetric{2}.D1);
 
             x_xi = D1Metric{1}*x;
             x_eta = D1Metric{2}*x;
@@ -157,7 +157,7 @@
             % D2 coefficients
             kappa_coeff = cell(dim,dim);
             for j = 1:dim
-                obj.D2_kappa{j} = sparse(m_tot,m_tot); 
+                obj.D2_kappa{j} = sparse(m_tot,m_tot);
                 kappa_coeff{j} = sparse(m_tot,1);
                 for i = 1:dim
                     kappa_coeff{j} = kappa_coeff{j} + b{i,j}*J*b{i,j}*kappa;
@@ -270,28 +270,20 @@
             default_arg('symmetric', false);
             default_arg('tuning',1.2);
 
-            % j is the coordinate direction of the boundary
-            % nj: outward unit normal component. 
+            % nj: outward unit normal component.
             % nj = -1 for west, south, bottom boundaries
             % nj = 1  for east, north, top boundaries
-            [j, nj] = obj.get_boundary_number(boundary);
-            switch nj
-            case 1
-                e = obj.e_r{j};
-                flux = obj.flux_r{j};
-                H_gamma = obj.H_boundary_r{j};
-            case -1
-                e = obj.e_l{j};
-                flux = obj.flux_l{j};
-                H_gamma = obj.H_boundary_l{j};
-            end
+            nj = obj.getBoundarySign(boundary);
+
+            Hi = obj.Hi;
+            [e, flux] = obj.getBoundaryOperator({'e', 'flux'}, boundary);
+            H_gamma = obj.getBoundaryQuadrature(boundary);
+            alpha = obj.getBoundaryBorrowing(boundary);
 
             Hi = obj.Hi;
             Ji = obj.Ji;
             KAPPA = obj.KAPPA;
-            kappa_gamma = e'*KAPPA*e; 
-            h = obj.h(j);
-            alpha = h*obj.alpha(j);
+            kappa_gamma = e'*KAPPA*e;
 
             switch type
 
@@ -299,19 +291,19 @@
             case {'D','d','dirichlet','Dirichlet'}
 
                 if ~symmetric
-                    closure = -Ji*Hi*flux'*e*H_gamma*(e' ); 
+                    closure = -Ji*Hi*flux'*e*H_gamma*(e' );
                     penalty = Ji*Hi*flux'*e*H_gamma;
                 else
                     closure = Ji*Hi*flux'*e*H_gamma*(e' )...
-                              -tuning*2/alpha*Ji*Hi*e*kappa_gamma*H_gamma*(e' ) ; 
+                              -tuning*2/alpha*Ji*Hi*e*kappa_gamma*H_gamma*(e' ) ;
                     penalty =  -Ji*Hi*flux'*e*H_gamma ...
                               +tuning*2/alpha*Ji*Hi*e*kappa_gamma*H_gamma;
                 end
 
             % Normal flux boundary condition
             case {'N','n','neumann','Neumann'}
-                    closure = -Ji*Hi*e*H_gamma*(e'*flux ); 
-                    penalty =  Ji*Hi*e*H_gamma; 
+                    closure = -Ji*Hi*e*H_gamma*(e'*flux );
+                    penalty =  Ji*Hi*e*H_gamma;
 
             % Unknown boundary condition
             otherwise
@@ -325,57 +317,103 @@
             error('Interface not implemented');
         end
 
-        % Returns the coordinate number and outward normal component for the boundary specified by the string boundary.
-        function [j, nj] = get_boundary_number(obj, boundary)
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
-            switch boundary
-                case {'w','W','west','West', 'e', 'E', 'east', 'East'}
-                    j = 1;
-                case {'s','S','south','South', 'n', 'N', 'north', 'North'}
-                    j = 2;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
+            if ~iscell(op)
+                op = {op};
             end
 
-            switch boundary
-                case {'w','W','west','West','s','S','south','South'}
-                    nj = -1;
-                case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                    nj = 1;
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'w'
+                        e = obj.e_l{1};
+                    case 'e'
+                        e = obj.e_r{1};
+                    case 's'
+                        e = obj.e_l{2};
+                    case 'n'
+                        e = obj.e_r{2};
+                    end
+                    varargout{i} = e;
+
+                case 'd'
+                    switch boundary
+                    case 'w'
+                        d = obj.d1_l{1};
+                    case 'e'
+                        d = obj.d1_r{1};
+                    case 's'
+                        d = obj.d1_l{2};
+                    case 'n'
+                        d = obj.d1_r{2};
+                    end
+                    varargout{i} = d;
+
+                case 'flux'
+                    switch boundary
+                    case 'w'
+                        flux = obj.flux_l{1};
+                    case 'e'
+                        flux = obj.flux_r{1};
+                    case 's'
+                        flux = obj.flux_l{2};
+                    case 'n'
+                        flux = obj.flux_r{2};
+                    end
+                    varargout{i} = flux;
+                end
             end
         end
 
-        % Returns the coordinate number and outward normal component for the boundary specified by the string boundary.
-        function [return_op] = get_boundary_operator(obj, op, boundary)
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
             switch boundary
-                case {'w','W','west','West', 'e', 'E', 'east', 'East'}
-                    j = 1;
-                case {'s','S','south','South', 'n', 'N', 'north', 'North'}
-                    j = 2;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
-            end
-
-            switch op
+                case 'w'
+                    H_b = obj.H_boundary_l{1};
                 case 'e'
-                    switch boundary
-                        case {'w','W','west','West','s','S','south','South'}
-                            return_op = obj.e_l{j};
-                        case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                            return_op = obj.e_r{j};
-                    end
-                case 'd'
-                    switch boundary
-                        case {'w','W','west','West','s','S','south','South'}
-                            return_op = obj.d1_l{j};
-                        case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                            return_op = obj.d1_r{j};
-                    end
-                otherwise
-                    error(['No such operator: operatr = ' op]);
+                    H_b = obj.H_boundary_r{1};
+                case 's'
+                    H_b = obj.H_boundary_l{2};
+                case 'n'
+                    H_b = obj.H_boundary_r{2};
             end
+        end
 
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'e','n'}
+                    s = 1;
+                case {'w','s'}
+                    s = -1;
+            end
+        end
+
+        % Returns borrowing constant gamma*h
+        % boundary -- string
+        function gamm = getBoundaryBorrowing(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'w','e'}
+                    gamm = obj.h(1)*obj.alpha(1);
+                case {'s','n'}
+                    gamm = obj.h(2)*obj.alpha(2);
+            end
         end
 
         function N = size(obj)
--- a/+scheme/Heat2dVariable.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Heat2dVariable.m	Tue Feb 12 17:12:42 2019 +0100
@@ -1,9 +1,9 @@
 classdef Heat2dVariable < scheme.Scheme
 
 % Discretizes the Laplacian with variable coefficent,
-% In the Heat equation way (i.e., the discretization matrix is not necessarily 
+% In the Heat equation way (i.e., the discretization matrix is not necessarily
 % symmetric)
-% u_t = div * (kappa * grad u ) 
+% u_t = div * (kappa * grad u )
 % opSet should be cell array of opSets, one per dimension. This
 % is useful if we have periodic BC in one direction.
 
@@ -29,7 +29,7 @@
         e_l, e_r
         d1_l, d1_r % Normal derivatives at the boundary
         alpha % Vector of borrowing constants
-        
+
         H_boundary % Boundary inner products
 
     end
@@ -162,26 +162,18 @@
             default_arg('symmetric', false);
             default_arg('tuning',1.2);
 
-            % j is the coordinate direction of the boundary
-            % nj: outward unit normal component. 
+            % nj: outward unit normal component.
             % nj = -1 for west, south, bottom boundaries
             % nj = 1  for east, north, top boundaries
-            [j, nj] = obj.get_boundary_number(boundary);
-            switch nj
-            case 1
-                e = obj.e_r;
-                d = obj.d1_r;
-            case -1
-                e = obj.e_l;
-                d = obj.d1_l;
-            end
+            nj = obj.getBoundarySign(boundary);
 
             Hi = obj.Hi;
-            H_gamma = obj.H_boundary{j};
+            [e, d] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            H_gamma = obj.getBoundaryQuadrature(boundary);
+            alpha = obj.getBoundaryBorrowing(boundary);
+
             KAPPA = obj.KAPPA;
-            kappa_gamma = e{j}'*KAPPA*e{j}; 
-            h = obj.h(j);
-            alpha = h*obj.alpha(j);
+            kappa_gamma = e'*KAPPA*e;
 
             switch type
 
@@ -189,19 +181,19 @@
             case {'D','d','dirichlet','Dirichlet'}
 
                 if ~symmetric
-                    closure = -nj*Hi*d{j}*kappa_gamma*H_gamma*(e{j}' ); 
-                    penalty =  nj*Hi*d{j}*kappa_gamma*H_gamma;
+                    closure = -nj*Hi*d*kappa_gamma*H_gamma*(e' );
+                    penalty =  nj*Hi*d*kappa_gamma*H_gamma;
                 else
-                    closure = nj*Hi*d{j}*kappa_gamma*H_gamma*(e{j}' )...
-                              -tuning*2/alpha*Hi*e{j}*kappa_gamma*H_gamma*(e{j}' ) ; 
-                    penalty =  -nj*Hi*d{j}*kappa_gamma*H_gamma ...
-                              +tuning*2/alpha*Hi*e{j}*kappa_gamma*H_gamma;
+                    closure = nj*Hi*d*kappa_gamma*H_gamma*(e' )...
+                              -tuning*2/alpha*Hi*e*kappa_gamma*H_gamma*(e' ) ;
+                    penalty =  -nj*Hi*d*kappa_gamma*H_gamma ...
+                              +tuning*2/alpha*Hi*e*kappa_gamma*H_gamma;
                 end
 
             % Free boundary condition
             case {'N','n','neumann','Neumann'}
-                    closure = -nj*Hi*e{j}*kappa_gamma*H_gamma*(d{j}' ); 
-                    penalty =  Hi*e{j}*kappa_gamma*H_gamma; 
+                    closure = -nj*Hi*e*kappa_gamma*H_gamma*(d' );
+                    penalty =  Hi*e*kappa_gamma*H_gamma;
                     % penalty is for normal derivative and not for derivative, hence the sign.
 
             % Unknown boundary condition
@@ -216,57 +208,90 @@
             error('Interface not implemented');
         end
 
-        % Returns the coordinate number and outward normal component for the boundary specified by the string boundary.
-        function [j, nj] = get_boundary_number(obj, boundary)
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
-            switch boundary
-                case {'w','W','west','West', 'e', 'E', 'east', 'East'}
-                    j = 1;
-                case {'s','S','south','South', 'n', 'N', 'north', 'North'}
-                    j = 2;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
+            if ~iscell(op)
+                op = {op};
             end
 
-            switch boundary
-                case {'w','W','west','West','s','S','south','South'}
-                    nj = -1;
-                case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                    nj = 1;
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'w'
+                        e = obj.e_l{1};
+                    case 'e'
+                        e = obj.e_r{1};
+                    case 's'
+                        e = obj.e_l{2};
+                    case 'n'
+                        e = obj.e_r{2};
+                    end
+                    varargout{i} = e;
+
+                case 'd'
+                    switch boundary
+                    case 'w'
+                        d = obj.d1_l{1};
+                    case 'e'
+                        d = obj.d1_r{1};
+                    case 's'
+                        d = obj.d1_l{2};
+                    case 'n'
+                        d = obj.d1_r{2};
+                    end
+                    varargout{i} = d;
+                end
             end
         end
 
-        % Returns the coordinate number and outward normal component for the boundary specified by the string boundary.
-        function [return_op] = get_boundary_operator(obj, op, boundary)
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
             switch boundary
-                case {'w','W','west','West', 'e', 'E', 'east', 'East'}
-                    j = 1;
-                case {'s','S','south','South', 'n', 'N', 'north', 'North'}
-                    j = 2;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
-            end
-
-            switch op
+                case 'w'
+                    H_b = obj.H_boundary{1};
                 case 'e'
-                    switch boundary
-                        case {'w','W','west','West','s','S','south','South'}
-                            return_op = obj.e_l{j};
-                        case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                            return_op = obj.e_r{j};
-                    end
-                case 'd'
-                    switch boundary
-                        case {'w','W','west','West','s','S','south','South'}
-                            return_op = obj.d1_l{j};
-                        case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
-                            return_op = obj.d1_r{j};
-                    end
-                otherwise
-                    error(['No such operator: operatr = ' op]);
+                    H_b = obj.H_boundary{1};
+                case 's'
+                    H_b = obj.H_boundary{2};
+                case 'n'
+                    H_b = obj.H_boundary{2};
             end
+        end
 
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'e','n'}
+                    s = 1;
+                case {'w','s'}
+                    s = -1;
+            end
+        end
+
+        % Returns borrowing constant gamma*h
+        % boundary -- string
+        function gamm = getBoundaryBorrowing(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'w','e'}
+                    gamm = obj.h(1)*obj.alpha(1);
+                case {'s','n'}
+                    gamm = obj.h(2)*obj.alpha(2);
+            end
         end
 
         function N = size(obj)
--- a/+scheme/Hypsyst2d.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Hypsyst2d.m	Tue Feb 12 17:12:42 2019 +0100
@@ -6,10 +6,10 @@
         x,y % Grid
         X,Y % Values of x and y for each grid point
         order % Order accuracy for the approximation
-        
+
         D % non-stabalized scheme operator
         A, B, E %Coefficient matrices
-        
+
         H % Discrete norm
         % Norms in the x and y directions
         Hxi,Hyi % Kroneckerd norms. 1'*Hx*v corresponds to integration in the x dir.
@@ -17,65 +17,65 @@
         e_w, e_e, e_s, e_n
         params %parameters for the coeficient matrice
     end
-    
+
     methods
         %Solving Hyperbolic systems on the form u_t=-Au_x-Bu_y-Eu
         function obj = Hypsyst2d(m, lim, order, A, B, E, params)
             default_arg('E', [])
             xlim = lim{1};
             ylim = lim{2};
-            
+
             if length(m) == 1
                 m = [m m];
             end
-            
+
             obj.A=A;
             obj.B=B;
             obj.E=E;
-            
+
             m_x = m(1);
             m_y = m(2);
             obj.params = params;
-            
+
             ops_x = sbp.D2Standard(m_x,xlim,order);
             ops_y = sbp.D2Standard(m_y,ylim,order);
-            
+
             obj.x = ops_x.x;
             obj.y = ops_y.x;
-            
+
             obj.X = kr(obj.x,ones(m_y,1));
             obj.Y = kr(ones(m_x,1),obj.y);
-            
+
             Aevaluated = obj.evaluateCoefficientMatrix(A, obj.X, obj.Y);
             Bevaluated = obj.evaluateCoefficientMatrix(B, obj.X, obj.Y);
             Eevaluated = obj.evaluateCoefficientMatrix(E, obj.X, obj.Y);
-            
+
             obj.n = length(A(obj.params,0,0));
-            
+
             I_n = eye(obj.n);I_x = speye(m_x);
             obj.I_x = I_x;
             I_y = speye(m_y);
             obj.I_y = I_y;
-            
-            
+
+
             D1_x = kr(I_n, ops_x.D1, I_y);
             obj.Hxi = kr(I_n, ops_x.HI, I_y);
             D1_y = kr(I_n, I_x, ops_y.D1);
             obj.Hyi = kr(I_n, I_x, ops_y.HI);
-            
+
             obj.e_w = kr(I_n, ops_x.e_l, I_y);
             obj.e_e = kr(I_n, ops_x.e_r, I_y);
             obj.e_s = kr(I_n, I_x, ops_y.e_l);
             obj.e_n = kr(I_n, I_x, ops_y.e_r);
-            
+
             obj.m = m;
             obj.h = [ops_x.h ops_y.h];
             obj.order = order;
-            
+
             obj.D = -Aevaluated*D1_x-Bevaluated*D1_y-Eevaluated;
-            
+
         end
-        
+
         % Closure functions return the opertors applied to the own doamin to close the boundary
         % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
         %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
@@ -92,18 +92,18 @@
                     error('No such boundary condition')
             end
         end
-        
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
-            error('An interface function does not exist yet');
+
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
+            error('Not implemented');
         end
-        
+
         function N = size(obj)
             N = obj.m;
         end
-        
+
         function [ret] = evaluateCoefficientMatrix(obj, mat, X, Y)
             params = obj.params;
-            
+
             if isa(mat,'function_handle')
                 [rows,cols] = size(mat(params,0,0));
                 matVec = mat(params,X',Y');
@@ -116,7 +116,7 @@
                 cols = cols/side;
             end
             ret = cell(rows,cols);
-            
+
             for ii = 1:rows
                 for jj=1:cols
                     ret{ii,jj} = diag(matVec(ii,(jj-1)*side+1:jj*side));
@@ -124,13 +124,13 @@
             end
             ret = cell2mat(ret);
         end
-        
+
         %Characteristic boundary conditions
         function [closure, penalty] = boundary_condition_char(obj,boundary)
             params = obj.params;
             x = obj.x;
             y = obj.y;
-            
+
             switch boundary
                 case {'w','W','west'}
                     e_ = obj.e_w;
@@ -164,7 +164,7 @@
             pos = signVec(1);
             zeroval = signVec(2);
             neg = signVec(3);
-            
+
             switch boundPos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -180,16 +180,16 @@
                     penalty = -Hi*e_*V*tau*Vi_minus;
             end
         end
-        
+
         % General boundary condition in the form Lu=g(x)
         function [closure,penalty] = boundary_condition_general(obj,boundary,L)
             params = obj.params;
             x = obj.x;
             y = obj.y;
-            
+            e_ = obj.getBoundaryOperator('e', boundary);
+
             switch boundary
                 case {'w','W','west'}
-                    e_ = obj.e_w;
                     mat = obj.A;
                     boundPos = 'l';
                     Hi = obj.Hxi;
@@ -197,7 +197,6 @@
                     L = obj.evaluateCoefficientMatrix(L,x(1),y);
                     side = max(length(y));
                 case {'e','E','east'}
-                    e_ = obj.e_e;
                     mat = obj.A;
                     boundPos = 'r';
                     Hi = obj.Hxi;
@@ -205,7 +204,6 @@
                     L = obj.evaluateCoefficientMatrix(L,x(end),y);
                     side = max(length(y));
                 case {'s','S','south'}
-                    e_ = obj.e_s;
                     mat = obj.B;
                     boundPos = 'l';
                     Hi = obj.Hyi;
@@ -213,19 +211,18 @@
                     L = obj.evaluateCoefficientMatrix(L,x,y(1));
                     side = max(length(x));
                 case {'n','N','north'}
-                    e_ = obj.e_n;
                     mat = obj.B;
                     boundPos = 'r';
                     Hi = obj.Hyi;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,x,y(end));
-                    L = obj.evaluateCoefficientMatrix(L,x,y(end));      
+                    L = obj.evaluateCoefficientMatrix(L,x,y(end));
                     side = max(length(x));
             end
-            
+
             pos = signVec(1);
             zeroval = signVec(2);
             neg = signVec(3);
-            
+
             switch boundPos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -233,7 +230,7 @@
                     Vi_minus = Vi(pos+zeroval+1:obj.n*side,:);
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos+zeroval)+1:obj.n*side);
-                    
+
                     tau(1:pos,:) = -abs(D(1:pos,1:pos));
                     R = -inv(L*V_plus)*(L*V_minus);
                     closure = Hi*e_*V*tau*(Vi_plus-R*Vi_minus)*e_';
@@ -243,7 +240,7 @@
                     tau((pos+zeroval)+1:obj.n*side,:) = -abs(D((pos+zeroval)+1:obj.n*side,(pos+zeroval)+1:obj.n*side));
                     Vi_plus = Vi(1:pos,:);
                     Vi_minus = Vi((pos+zeroval)+1:obj.n*side,:);
-                    
+
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos+zeroval)+1:obj.n*side);
                     R = -inv(L*V_minus)*(L*V_plus);
@@ -251,13 +248,13 @@
                     penalty = -Hi*e_*V*tau*inv(L*V_minus)*L;
             end
         end
-        
+
         % Function that diagonalizes a symbolic matrix A as A=V*D*Vi
         % D         is a diagonal matrix with the eigenvalues on A on the diagonal sorted by their sign
         %                                    [d+       ]
         %                               D =  [   d0    ]
         %                                    [       d-]
-        % signVec   is a vector specifying the number of possitive, zero and negative eigenvalues of D   
+        % signVec   is a vector specifying the number of possitive, zero and negative eigenvalues of D
         function [V,Vi, D,signVec] = matrixDiag(obj,mat,x,y)
             params = obj.params;
             syms xs ys
@@ -265,12 +262,12 @@
             Vi = inv(V);
             xs = x;
             ys = y;
-            
+
             side = max(length(x),length(y));
             Dret = zeros(obj.n,side*obj.n);
             Vret = zeros(obj.n,side*obj.n);
             Viret = zeros(obj.n,side*obj.n);
-            
+
             for ii = 1:obj.n
                 for jj = 1:obj.n
                     Dret(jj,(ii-1)*side+1:side*ii) = eval(D(jj,ii));
@@ -278,7 +275,7 @@
                     Viret(jj,(ii-1)*side+1:side*ii) = eval(Vi(jj,ii));
                 end
             end
-            
+
             D = sparse(Dret);
             V = sparse(Vret);
             Vi = sparse(Viret);
@@ -286,16 +283,65 @@
             Vi = obj.evaluateCoefficientMatrix(Vi,x,y);
             D = obj.evaluateCoefficientMatrix(D,x,y);
             DD = diag(D);
-            
+
             poseig = (DD>0);
             zeroeig = (DD==0);
             negeig = (DD<0);
-            
+
             D = diag([DD(poseig); DD(zeroeig); DD(negeig)]);
             V = [V(:,poseig) V(:,zeroeig) V(:,negeig)];
             Vi = [Vi(poseig,:); Vi(zeroeig,:); Vi(negeig,:)];
             signVec = [sum(poseig),sum(zeroeig),sum(negeig)];
         end
-        
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            if ~iscell(op)
+                op = {op};
+            end
+
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'w'
+                        e = obj.e_w;
+                    case 'e'
+                        e = obj.e_e;
+                    case 's'
+                        e = obj.e_s;
+                    case 'n'
+                        e = obj.e_n;
+                    end
+                    varargout{i} = e;
+                end
+            end
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            e = obj.getBoundaryOperator('e', boundary);
+
+            switch boundary
+                case 'w'
+                    H_b = inv(e'*obj.Hyi*e);
+                case 'e'
+                    H_b = inv(e'*obj.Hyi*e);
+                case 's'
+                    H_b = inv(e'*obj.Hxi*e);
+                case 'n'
+                    H_b = inv(e'*obj.Hxi*e);
+            end
+        end
+
     end
 end
\ No newline at end of file
--- a/+scheme/Hypsyst2dCurve.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Hypsyst2dCurve.m	Tue Feb 12 17:12:42 2019 +0100
@@ -4,19 +4,19 @@
         n % size of system
         h % Grid spacing
         X,Y % Values of x and y for each grid point
-        
+
         J, Ji % Jacobaian and inverse Jacobian
         xi,eta
         Xi,Eta
-        
+
         A,B
         X_eta, Y_eta
         X_xi,Y_xi
         order % Order accuracy for the approximation
-        
+
         D % non-stabalized scheme operator
         Ahat, Bhat, E
-        
+
         H % Discrete norm
         Hxii,Hetai % Kroneckerd norms in xi and eta.
         I_xi,I_eta, I_N, onesN
@@ -24,93 +24,93 @@
         index_w, index_e,index_s,index_n
         params % Parameters for the coeficient matrice
     end
-    
-    
+
+
     methods
         % Solving Hyperbolic systems on the form u_t=-Au_x-Bu_y-Eu
         function obj = Hypsyst2dCurve(m, order, A, B, E, params, ti)
             default_arg('E', [])
             xilim = {0 1};
             etalim = {0 1};
-            
+
             if length(m) == 1
                 m = [m m];
             end
             obj.params = params;
             obj.A=A;
             obj.B=B;
-            
+
             obj.Ahat=@(params,x,y,x_eta,y_eta)(A(params,x,y).*y_eta-B(params,x,y).*x_eta);
             obj.Bhat=@(params,x,y,x_xi,y_xi)(B(params,x,y).*x_xi-A(params,x,y).*y_xi);
             obj.E=@(params,x,y,~,~)E(params,x,y);
-            
+
             m_xi = m(1);
             m_eta = m(2);
             m_tot=m_xi*m_eta;
-            
+
             ops_xi = sbp.D2Standard(m_xi,xilim,order);
             ops_eta = sbp.D2Standard(m_eta,etalim,order);
-            
+
             obj.xi = ops_xi.x;
             obj.eta = ops_eta.x;
-            
+
             obj.Xi = kr(obj.xi,ones(m_eta,1));
             obj.Eta = kr(ones(m_xi,1),obj.eta);
-            
+
             obj.n = length(A(obj.params,0,0));
             obj.onesN=ones(obj.n);
-            
+
             obj.index_w=1:m_eta;
-            obj.index_e=(m_tot-m_e        
-        
+            obj.index_e=(m_tot-m_e
+
         metric_termsta+1):m_tot;
             obj.index_s=1:m_eta:(m_tot-m_eta+1);
             obj.index_n=(m_eta):m_eta:m_tot;
-            
+
             I_n = eye(obj.n);
             I_xi = speye(m_xi);
             obj.I_xi = I_xi;
             I_eta = speye(m_eta);
             obj.I_eta = I_eta;
-            
+
             D1_xi = kr(I_n, ops_xi.D1, I_eta);
             obj.Hxii = kr(I_n, ops_xi.HI, I_eta);
             D1_eta = kr(I_n, I_xi, ops_eta.D1);
             obj.Hetai = kr(I_n, I_xi, ops_eta.HI);
-            
+
             obj.e_w = kr(I_n, ops_xi.e_l, I_eta);
             obj.e_e = kr(I_n, ops_xi.e_r, I_eta);
             obj.e_s = kr(I_n, I_xi, ops_eta.e_l);
-            obj.e_n = kr(I_n, I_xi,         
-        
+            obj.e_n = kr(I_n, I_xi,
+
         metric_termsops_eta.e_r);
-            
+
             [X,Y] = ti.map(obj.xi,obj.eta);
-            
+
             [x_xi,x_eta] = gridDerivatives(X,ops_xi.D1,ops_eta.D1);
             [y_xi,y_eta] = gridDerivatives(Y,ops_xi.D1, ops_eta.D1);
-            
+
             obj.X = reshape(X,m_tot,1);
             obj.Y = reshape(Y,m_tot,1);
             obj.X_xi = reshape(x_xi,m_tot,1);
             obj.Y_xi = reshape(y_xi,m_tot,1);
             obj.X_eta = reshape(x_eta,m_tot,1);
             obj.Y_eta = reshape(y_eta,m_tot,1);
-            
+
             Ahat_evaluated = obj.evaluateCoefficientMatrix(obj.Ahat, obj.X, obj.Y,obj.X_eta,obj.Y_eta);
             Bhat_evaluated = obj.evaluateCoefficientMatrix(obj.Bhat, obj.X, obj.Y,obj.X_xi,obj.Y_xi);
             E_evaluated = obj.evaluateCoefficientMatrix(obj.E, obj.X, obj.Y,[],[]);
-            
+
             obj.m = m;
             obj.h = [ops_xi.h ops_eta.h];
             obj.order = order;
             obj.J = obj.X_xi.*obj.Y_eta - obj.X_eta.*obj.Y_xi;
             obj.Ji = kr(I_n,spdiags(1./obj.J,0,m_tot,m_tot));
-            
+
             obj.D = obj.Ji*(-Ahat_evaluated*D1_xi-Bhat_evaluated*D1_eta)-E_evaluated;
-            
+
         end
-        
+
         % Closure functions return the opertors applied to the own doamin to close the boundary
         % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
         %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w',General boundary conditions'n','s'.
@@ -127,18 +127,18 @@
                     error('No such boundary condition')
             end
         end
-        
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundaryGeneral boundary conditions)
-            error('An interface function does not exist yet');
+
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
+            error('Not implemented');
         end
-        
+
         function N = size(obj)
             N = obj.m;
         end
-        
+
         function [ret] = evaluateCoefficientMatrix(obj, mat, X, Y,x_,y_)
             params = obj.params;
-            
+
             if isa(mat,'function_handle')
                 [rows,cols] = size(mat(params,0,0,0,0));
                 x_ = kr(obj.onesN,x_);
@@ -152,7 +152,7 @@
                 side = max(length(X),length(Y));
                 cols = cols/side;
             end
-            
+
             ret = cell(rows,cols);
             for ii = 1:rows
                 for jj = 1:cols
@@ -161,7 +161,7 @@
             end
             ret = cell2mat(ret);
         end
-        
+
         %Characteristic boundary conditions
         function [closure, penalty] = boundary_condition_char(obj,boundary)
             params = obj.params;
@@ -169,42 +169,39 @@
             Y = obj.Y;
             xi = obj.xi;
             eta = obj.eta;
-            
+            e_ = obj.getBoundaryOperator('e', boundary);
+
             switch boundary
                 case {'w','W','west'}
-                    e_ = obj.e_w;
                     mat = obj.Ahat;
                     boundPos = 'l';
                     Hi = obj.Hxii;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_w),Y(obj.index_w),obj.X_eta(obj.index_w),obj.Y_eta(obj.index_w));
                     side = max(length(eta));
                 case {'e','E','east'}
-                    e_ = obj.e_e;
                     mat = obj.Ahat;
                     boundPos = 'r';
                     Hi = obj.Hxii;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_e),Y(obj.index_e),obj.X_eta(obj.index_e),obj.Y_eta(obj.index_e));
                     side = max(length(eta));
                 case {'s','S','south'}
-                    e_ = obj.e_s;
                     mat = obj.Bhat;
                     boundPos = 'l';
                     Hi = obj.Hetai;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_s),Y(obj.index_s),obj.X_xi(obj.index_s),obj.Y_xi(obj.index_s));
                     side = max(length(xi));
                 case {'n','N','north'}
-                    e_ = obj.e_n;
                     mat = obj.Bhat;
                     boundPos = 'r';
                     Hi = obj.Hetai;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_n),Y(obj.index_n),obj.X_xi(obj.index_n),obj.Y_xi(obj.index_n));
                     side = max(length(xi));
             end
-            
+
             pos = signVec(1);
             zeroval = signVec(2);
             neg = signVec(3);
-            
+
             switch boundPos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -218,10 +215,10 @@
                     Vi_minus = Vi((pos+zeroval)+1:obj.n*side,:);
                     closure = Hi*e_*V*tau*Vi_minus*e_';
                     penalty = -Hi*e_*V*tau*Vi_minus;
-            end  
+            end
         end
-        
-        
+
+
         % General boundary condition in the form Lu=g(x)
         function [closure,penalty] = boundary_condition_general(obj,boundary,L)
             params = obj.params;
@@ -229,7 +226,7 @@
             Y = obj.Y;
             xi = obj.xi;
             eta = obj.eta;
-            
+
             switch boundary
                 case {'w','W','west'}
                     e_ = obj.e_w;
@@ -237,7 +234,7 @@
                     boundPos = 'l';
                     Hi = obj.Hxii;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_w),Y(obj.index_w),obj.X_eta(obj.index_w),obj.Y_eta(obj.index_w));
-                    
+
                     Ji_vec = diag(obj.Ji);
                     Ji = diag(Ji_vec(obj.index_w));
                     xi_x = Ji*obj.Y_eta(obj.index_w);
@@ -250,7 +247,7 @@
                     boundPos = 'r';
                     Hi = obj.Hxii;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_e),Y(obj.index_e),obj.X_eta(obj.index_e),obj.Y_eta(obj.index_e));
-                    
+
                     Ji_vec = diag(obj.Ji);
                     Ji = diag(Ji_vec(obj.index_e));
                     xi_x = Ji*obj.Y_eta(obj.index_e);
@@ -263,7 +260,7 @@
                     boundPos = 'l';
                     Hi = obj.Hetai;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_s),Y(obj.index_s),obj.X_xi(obj.index_s),obj.Y_xi(obj.index_s));
-                    
+
                     Ji_vec = diag(obj.Ji);
                     Ji = diag(Ji_vec(obj.index_s));
                     eta_x = Ji*obj.Y_xi(obj.index_s);
@@ -276,7 +273,7 @@
                     boundPos = 'r';
                     Hi = obj.Hetai;
                     [V,Vi,D,signVec] = obj.matrixDiag(mat,X(obj.index_n),Y(obj.index_n),obj.X_xi(obj.index_n),obj.Y_xi(obj.index_n));
-                    
+
                     Ji_vec = diag(obj.Ji);
                     Ji = diag(Ji_vec(obj.index_n));
                     eta_x = Ji*obj.Y_xi(obj.index_n);
@@ -284,11 +281,11 @@
                     L = obj.evaluateCoefficientMatrix(L,-eta_x,-eta_y,[],[]);
                     side = max(length(xi));
             end
-            
+
             pos = signVec(1);
             zeroval = signVec(2);
             neg = signVec(3);
-            
+
             switch boundPos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -296,7 +293,7 @@
                     Vi_minus = Vi(pos+1:obj.n*side,:);
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos)+1:obj.n*side);
-                    
+
                     tau(1:pos,:) = -abs(D(1:pos,1:pos));
                     R = -inv(L*V_plus)*(L*V_minus);
                     closure = Hi*e_*V*tau*(Vi_plus-R*Vi_minus)*e_';
@@ -306,7 +303,7 @@
                     tau((pos+zeroval)+1:obj.n*side,:) = -abs(D((pos+zeroval)+1:obj.n*side,(pos+zeroval)+1:obj.n*side));
                     Vi_plus = Vi(1:pos,:);
                     Vi_minus = Vi((pos+zeroval)+1:obj.n*side,:);
-                    
+
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos+zeroval)+1:obj.n*side);
                     R = -inv(L*V_minus)*(L*V_plus);
@@ -314,7 +311,7 @@
                     penalty = -Hi*e_*V*tau*inv(L*V_minus)*L;
             end
         end
-                        
+
         % Function that diagonalizes a symbolic matrix A as A=V*D*Vi
         % D         is a diagonal matrix with the eigenvalues on A on the diagonal sorted by their sign
         %                                    [d+       ]
@@ -329,22 +326,22 @@
             else
                 xs_ = 0;
             end
-            
+
             if(sum(abs(y_))~= 0)
                 syms ys_;
             else
                 ys_ = 0;
             end
-            
+
             [V, D] = eig(mat(params,xs,ys,xs_,ys_));
             Vi = inv(V);
             syms xs ys xs_ ys_
-            
+
             xs = x;
             ys = y;
             xs_ = x_;
             ys_ = y_;
-            
+
             side = max(length(x),length(y));
             Dret = zeros(obj.n,side*obj.n);
             Vret = zeros(obj.n,side*obj.n);
@@ -356,7 +353,7 @@
                     Viret(jj,(ii-1)*side+1:side*ii) = eval(Vi(jj,ii));
                 end
             end
-            
+
             D = sparse(Dret);
             V = sparse(Vret);
             Vi = sparse(Viret);
@@ -364,15 +361,66 @@
             D = obj.evaluateCoefficientMatrix(D,x,y,x_,y_);
             Vi = obj.evaluateCoefficientMatrix(Vi,x,y,x_,y_);
             DD = diag(D);
-            
+
             poseig = (DD>0);
             zeroeig = (DD==0);
             negeig = (DD<0);
-            
+
             D = diag([DD(poseig); DD(zeroeig); DD(negeig)]);
             V = [V(:,poseig) V(:,zeroeig) V(:,negeig)];
             Vi = [Vi(poseig,:); Vi(zeroeig,:); Vi(negeig,:)];
             signVec = [sum(poseig),sum(zeroeig),sum(negeig)];
         end
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            if ~iscell(op)
+                op = {op};
+            end
+
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'w'
+                        e = obj.e_w;
+                    case 'e'
+                        e = obj.e_e;
+                    case 's'
+                        e = obj.e_s;
+                    case 'n'
+                        e = obj.e_n;
+                    end
+                    varargout{i} = e;
+                end
+            end
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            e = obj.getBoundaryOperator('e', boundary);
+
+            switch boundary
+                case 'w'
+                    H_b = inv(e'*obj.Hetai*e);
+                case 'e'
+                    H_b = inv(e'*obj.Hetai*e);
+                case 's'
+                    H_b = inv(e'*obj.Hxii*e);
+                case 'n'
+                    H_b = inv(e'*obj.Hxii*e);
+            end
+        end
+
+
     end
 end
\ No newline at end of file
--- a/+scheme/Hypsyst3d.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Hypsyst3d.m	Tue Feb 12 17:12:42 2019 +0100
@@ -7,11 +7,11 @@
         X, Y, Z% Values of x and y for each grid point
         Yx, Zx, Xy, Zy, Xz, Yz %Grid values for boundary surfaces
         order % Order accuracy for the approximation
-        
+
         D % non-stabalized scheme operator
         A, B, C, E % Symbolic coefficient matrices
         Aevaluated,Bevaluated,Cevaluated, Eevaluated
-        
+
         H % Discrete norm
         Hx, Hy, Hz  % Norms in the x, y and z directions
         Hxi,Hyi, Hzi % Kroneckerd norms. 1'*Hx*v corresponds to integration in the x dir.
@@ -19,8 +19,8 @@
         e_w, e_e, e_s, e_n, e_b, e_t
         params % Parameters for the coeficient matrice
     end
-    
-    
+
+
     methods
         % Solving Hyperbolic systems on the form u_t=-Au_x-Bu_y-Cu_z-Eu
         function obj = Hypsyst3d(m, lim, order, A, B,C, E, params,operator)
@@ -28,11 +28,11 @@
             xlim =  lim{1};
             ylim = lim{2};
             zlim = lim{3};
-            
+
             if length(m) == 1
                 m = [m m m];
             end
-            
+
             obj.A = A;
             obj.B = B;
             obj.C = C;
@@ -41,7 +41,7 @@
             m_y = m(2);
             m_z = m(3);
             obj.params = params;
-            
+
             switch operator
                 case 'upwind'
                     ops_x = sbp.D1Upwind(m_x,xlim,order);
@@ -52,29 +52,29 @@
                     ops_y = sbp.D2Standard(m_y,ylim,order);
                     ops_z = sbp.D2Standard(m_z,zlim,order);
             end
-            
+
             obj.x = ops_x.x;
             obj.y = ops_y.x;
             obj.z = ops_z.x;
-            
+
             obj.X = kr(obj.x,ones(m_y,1),ones(m_z,1));
             obj.Y = kr(ones(m_x,1),obj.y,ones(m_z,1));
             obj.Z = kr(ones(m_x,1),ones(m_y,1),obj.z);
-            
+
             obj.Yx = kr(obj.y,ones(m_z,1));
             obj.Zx = kr(ones(m_y,1),obj.z);
             obj.Xy = kr(obj.x,ones(m_z,1));
             obj.Zy = kr(ones(m_x,1),obj.z);
             obj.Xz = kr(obj.x,ones(m_y,1));
             obj.Yz = kr(ones(m_z,1),obj.y);
-            
+
             obj.Aevaluated = obj.evaluateCoefficientMatrix(A, obj.X, obj.Y,obj.Z);
             obj.Bevaluated = obj.evaluateCoefficientMatrix(B, obj.X, obj.Y,obj.Z);
             obj.Cevaluated = obj.evaluateCoefficientMatrix(C, obj.X, obj.Y,obj.Z);
             obj.Eevaluated = obj.evaluateCoefficientMatrix(E, obj.X, obj.Y,obj.Z);
-            
+
             obj.n = length(A(obj.params,0,0,0));
-            
+
             I_n = speye(obj.n);
             I_x = speye(m_x);
             obj.I_x = I_x;
@@ -83,31 +83,31 @@
             I_z = speye(m_z);
             obj.I_z = I_z;
             I_N = kr(I_n,I_x,I_y,I_z);
-            
+
             obj.Hxi = kr(I_n, ops_x.HI, I_y,I_z);
             obj.Hx = ops_x.H;
             obj.Hyi = kr(I_n, I_x, ops_y.HI,I_z);
             obj.Hy = ops_y.H;
             obj.Hzi = kr(I_n, I_x,I_y, ops_z.HI);
             obj.Hz = ops_z.H;
-            
+
             obj.e_w = kr(I_n, ops_x.e_l, I_y,I_z);
             obj.e_e = kr(I_n, ops_x.e_r, I_y,I_z);
             obj.e_s = kr(I_n, I_x, ops_y.e_l,I_z);
             obj.e_n = kr(I_n, I_x, ops_y.e_r,I_z);
             obj.e_b = kr(I_n, I_x, I_y, ops_z.e_l);
             obj.e_t = kr(I_n, I_x, I_y, ops_z.e_r);
-            
+
             obj.m = m;
             obj.h = [ops_x.h ops_y.h ops_x.h];
             obj.order = order;
-            
+
             switch operator
                 case 'upwind'
                     alphaA = max(abs(eig(A(params,obj.x(end),obj.y(end),obj.z(end)))));
                     alphaB = max(abs(eig(B(params,obj.x(end),obj.y(end),obj.z(end)))));
                     alphaC = max(abs(eig(C(params,obj.x(end),obj.y(end),obj.z(end)))));
-                    
+
                     Ap = (obj.Aevaluated+alphaA*I_N)/2;
                     Am = (obj.Aevaluated-alphaA*I_N)/2;
                     Dpx = kr(I_n, ops_x.Dp, I_y,I_z);
@@ -116,7 +116,7 @@
                     temp = Ap*Dmx;
                     obj.D = obj.D-temp;
                     clear Ap Am Dpx Dmx
-                    
+
                     Bp = (obj.Bevaluated+alphaB*I_N)/2;
                     Bm = (obj.Bevaluated-alphaB*I_N)/2;
                     Dpy = kr(I_n, I_x, ops_y.Dp,I_z);
@@ -126,20 +126,20 @@
                     temp = Bp*Dmy;
                     obj.D = obj.D-temp;
                     clear Bp Bm Dpy Dmy
-                    
-                    
+
+
                     Cp = (obj.Cevaluated+alphaC*I_N)/2;
                     Cm = (obj.Cevaluated-alphaC*I_N)/2;
                     Dpz = kr(I_n, I_x, I_y,ops_z.Dp);
                     Dmz = kr(I_n, I_x, I_y,ops_z.Dm);
-                    
+
                     temp = Cm*Dpz;
                     obj.D = obj.D-temp;
                     temp = Cp*Dmz;
                     obj.D = obj.D-temp;
                     clear Cp Cm Dpz Dmz
                     obj.D = obj.D-obj.Eevaluated;
-                    
+
                 case 'standard'
                     D1_x = kr(I_n, ops_x.D1, I_y,I_z);
                     D1_y = kr(I_n, I_x, ops_y.D1,I_z);
@@ -149,7 +149,7 @@
                     error('Opperator not supported');
             end
         end
-        
+
         % Closure functions return the opertors applied to the own doamin to close the boundary
         % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
         %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
@@ -167,15 +167,15 @@
                     error('No such boundary condition')
             end
         end
-        
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
-            error('An interface function does not exist yet');
+
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
+            error('Not implemented');
         end
-        
+
         function N = size(obj)
             N = obj.m;
         end
-        
+
         function [ret] = evaluateCoefficientMatrix(obj, mat, X, Y, Z)
             params = obj.params;
             side = max(length(X),length(Y));
@@ -189,7 +189,7 @@
                 side = max(length(X),length(Y));
                 cols = cols/side;
             end
-            
+
             ret = cell(rows,cols);
             for ii = 1:rows
                 for jj = 1:cols
@@ -198,10 +198,10 @@
             end
             ret = cell2mat(ret);
         end
-        
+
         function [BM] = boundary_matrices(obj,boundary)
             params = obj.params;
-            
+
             switch boundary
                 case {'w','W','west'}
                     BM.e_ = obj.e_w;
@@ -248,7 +248,7 @@
             end
             BM.pos = signVec(1); BM.zeroval=signVec(2); BM.neg=signVec(3);
         end
-        
+
         % Characteristic bouyndary consitions
         function [closure, penalty]=boundary_condition_char(obj,BM)
             side = BM.side;
@@ -260,7 +260,7 @@
             Hi = BM.Hi;
             D = BM.D;
             e_ = BM.e_;
-            
+
             switch BM.boundpos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -276,9 +276,9 @@
                     penalty = -Hi*e_*V*tau*Vi_minus;
             end
         end
-        
+
         % General boundary condition in the form Lu=g(x)
-        function [closure,penalty] = boundary_condition_general(obj,BM,boundary,L)           
+        function [closure,penalty] = boundary_condition_general(obj,BM,boundary,L)
             side = BM.side;
             pos = BM.pos;
             neg = BM.neg;
@@ -288,7 +288,7 @@
             Hi = BM.Hi;
             D = BM.D;
             e_ = BM.e_;
-            
+
             switch boundary
                 case {'w','W','west'}
                     L = obj.evaluateCoefficientMatrix(L,obj.x(1),obj.Yx,obj.Zx);
@@ -303,7 +303,7 @@
                 case {'t','T','top'}
                     L = obj.evaluateCoefficientMatrix(L,obj.Xz,obj.Yz,obj.z(end));
             end
-            
+
             switch BM.boundpos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -311,7 +311,7 @@
                     Vi_minus = Vi(pos+zeroval+1:obj.n*side,:);
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos+zeroval)+1:obj.n*side);
-                    
+
                     tau(1:pos,:) = -abs(D(1:pos,1:pos));
                     R = -inv(L*V_plus)*(L*V_minus);
                     closure = Hi*e_*V*tau*(Vi_plus-R*Vi_minus)*e_';
@@ -321,7 +321,7 @@
                     tau((pos+zeroval)+1:obj.n*side,:) = -abs(D((pos+zeroval)+1:obj.n*side,(pos+zeroval)+1:obj.n*side));
                     Vi_plus = Vi(1:pos,:);
                     Vi_minus = Vi((pos+zeroval)+1:obj.n*side,:);
-                    
+
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos+zeroval)+1:obj.n*side);
                     R = -inv(L*V_minus)*(L*V_plus);
@@ -329,7 +329,7 @@
                     penalty = -Hi*e_*V*tau*inv(L*V_minus)*L;
             end
         end
-        
+
         % Function that diagonalizes a symbolic matrix A as A=V*D*Vi
         % D         is a diagonal matrix with the eigenvalues on A on the diagonal sorted by their sign
         %                                    [d+       ]
@@ -344,13 +344,13 @@
             xs = x;
             ys = y;
             zs = z;
-            
-            
+
+
             side = max(length(x),length(y));
             Dret = zeros(obj.n,side*obj.n);
             Vret = zeros(obj.n,side*obj.n);
             Viret= zeros(obj.n,side*obj.n);
-           
+
             for ii=1:obj.n
                 for jj=1:obj.n
                     Dret(jj,(ii-1)*side+1:side*ii) = eval(D(jj,ii));
@@ -358,7 +358,7 @@
                     Viret(jj,(ii-1)*side+1:side*ii) = eval(Vi(jj,ii));
                 end
             end
-            
+
             D = sparse(Dret);
             V = sparse(Vret);
             Vi = sparse(Viret);
@@ -366,11 +366,11 @@
             Vi= obj.evaluateCoefficientMatrix(Vi,x,y,z);
             D = obj.evaluateCoefficientMatrix(D,x,y,z);
             DD = diag(D);
-            
+
             poseig = (DD>0);
             zeroeig = (DD==0);
             negeig = (DD<0);
-            
+
             D = diag([DD(poseig); DD(zeroeig); DD(negeig)]);
             V = [V(:,poseig) V(:,zeroeig) V(:,negeig)];
             Vi= [Vi(poseig,:); Vi(zeroeig,:); Vi(negeig,:)];
--- a/+scheme/Hypsyst3dCurve.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Hypsyst3dCurve.m	Tue Feb 12 17:12:42 2019 +0100
@@ -5,22 +5,22 @@
         h % Grid spacing
         X, Y, Z% Values of x and y for each grid point
         Yx, Zx, Xy, Zy, Xz, Yz %Grid values for boundary surfaces
-        
+
         xi,eta,zeta
         Xi, Eta, Zeta
-        
+
         Eta_xi, Zeta_xi, Xi_eta, Zeta_eta, Xi_zeta, Eta_zeta    % Metric terms
         X_xi, X_eta, X_zeta,Y_xi,Y_eta,Y_zeta,Z_xi,Z_eta,Z_zeta % Metric terms
-        
+
         order % Order accuracy for the approximation
-        
+
         D % non-stabalized scheme operator
         Aevaluated, Bevaluated, Cevaluated, Eevaluated % Numeric Coeffiecient matrices
         Ahat, Bhat, Chat  % Symbolic Transformed Coefficient matrices
         A, B, C, E % Symbolic coeffiecient matrices
-        
+
         J, Ji % JAcobian and inverse Jacobian
-        
+
         H % Discrete norm
         % Norms in the x, y and z directions
         Hxii,Hetai,Hzetai, Hzi % Kroneckerd norms. 1'*Hx*v corresponds to integration in the x dir.
@@ -30,14 +30,14 @@
         index_w, index_e,index_s,index_n, index_b, index_t
         params %parameters for the coeficient matrice
     end
-    
-    
+
+
     methods
         function obj = Hypsyst3dCurve(m, order, A, B,C, E, params,ti,operator)
             xilim ={0 1};
             etalim = {0 1};
             zetalim = {0 1};
-            
+
             if length(m) == 1
                 m = [m m m];
             end
@@ -47,11 +47,11 @@
             m_tot = m_xi*m_eta*m_zeta;
             obj.params = params;
             obj.n = length(A(obj,0,0,0));
-            
+
             obj.m = m;
             obj.order = order;
             obj.onesN = ones(obj.n);
-            
+
             switch operator
                 case 'upwind'
                     ops_xi = sbp.D1Upwind(m_xi,xilim,order);
@@ -64,21 +64,21 @@
                 otherwise
                     error('Operator not available')
             end
-            
+
             obj.xi = ops_xi.x;
             obj.eta = ops_eta.x;
             obj.zeta = ops_zeta.x;
-            
+
             obj.Xi = kr(obj.xi,ones(m_eta,1),ones(m_zeta,1));
             obj.Eta = kr(ones(m_xi,1),obj.eta,ones(m_zeta,1));
             obj.Zeta = kr(ones(m_xi,1),ones(m_eta,1),obj.zeta);
-            
-            
+
+
             [X,Y,Z] = ti.map(obj.Xi,obj.Eta,obj.Zeta);
             obj.X = X;
             obj.Y = Y;
             obj.Z = Z;
-            
+
             I_n = eye(obj.n);
             I_xi = speye(m_xi);
             obj.I_xi = I_xi;
@@ -86,19 +86,19 @@
             obj.I_eta = I_eta;
             I_zeta = speye(m_zeta);
             obj.I_zeta = I_zeta;
-            
+
             I_N=kr(I_n,I_xi,I_eta,I_zeta);
-            
+
             O_xi = ones(m_xi,1);
             O_eta = ones(m_eta,1);
             O_zeta = ones(m_zeta,1);
-            
-            
+
+
             obj.Hxi = ops_xi.H;
             obj.Heta = ops_eta.H;
             obj.Hzeta = ops_zeta.H;
             obj.h = [ops_xi.h ops_eta.h ops_zeta.h];
-            
+
             switch operator
                 case 'upwind'
                     D1_xi = kr((ops_xi.Dp+ops_xi.Dm)/2, I_eta,I_zeta);
@@ -109,11 +109,11 @@
                     D1_eta = kr(I_xi, ops_eta.D1,I_zeta);
                     D1_zeta = kr(I_xi, I_eta,ops_zeta.D1);
             end
-            
+
             obj.A = A;
             obj.B = B;
             obj.C = C;
-            
+
             obj.X_xi = D1_xi*X;
             obj.X_eta = D1_eta*X;
             obj.X_zeta = D1_zeta*X;
@@ -123,55 +123,55 @@
             obj.Z_xi = D1_xi*Z;
             obj.Z_eta = D1_eta*Z;
             obj.Z_zeta = D1_zeta*Z;
-            
+
             obj.Ahat = @transform_coefficient_matrix;
             obj.Bhat = @transform_coefficient_matrix;
             obj.Chat = @transform_coefficient_matrix;
             obj.E = @(obj,x,y,z,~,~,~,~,~,~)E(obj,x,y,z);
-            
+
             obj.Aevaluated = obj.evaluateCoefficientMatrix(obj.Ahat,obj.X, obj.Y,obj.Z, obj.X_eta,obj.X_zeta,obj.Y_eta,obj.Y_zeta,obj.Z_eta,obj.Z_zeta);
             obj.Bevaluated = obj.evaluateCoefficientMatrix(obj.Bhat,obj.X, obj.Y,obj.Z, obj.X_zeta,obj.X_xi,obj.Y_zeta,obj.Y_xi,obj.Z_zeta,obj.Z_xi);
             obj.Cevaluated = obj.evaluateCoefficientMatrix(obj.Chat,obj.X,obj.Y,obj.Z, obj.X_xi,obj.X_eta,obj.Y_xi,obj.Y_eta,obj.Z_xi,obj.Z_eta);
-            
+
             switch operator
                 case 'upwind'
                     clear  D1_xi D1_eta D1_zeta
                     alphaA = max(abs(eig(obj.Ahat(obj,obj.X(end), obj.Y(end),obj.Z(end), obj.X_eta(end),obj.X_zeta(end),obj.Y_eta(end),obj.Y_zeta(end),obj.Z_eta(end),obj.Z_zeta(end)))));
                     alphaB = max(abs(eig(obj.Bhat(obj,obj.X(end), obj.Y(end),obj.Z(end), obj.X_zeta(end),obj.X_xi(end),obj.Y_zeta(end),obj.Y_xi(end),obj.Z_zeta(end),obj.Z_xi(end)))));
                     alphaC = max(abs(eig(obj.Chat(obj,obj.X(end), obj.Y(end),obj.Z(end), obj.X_xi(end),obj.X_eta(end),obj.Y_xi(end),obj.Y_eta(end),obj.Z_xi(end),obj.Z_eta(end)))));
-                    
+
                     Ap = (obj.Aevaluated+alphaA*I_N)/2;
                     Dmxi = kr(I_n, ops_xi.Dm, I_eta,I_zeta);
                     diffSum = -Ap*Dmxi;
                     clear Ap Dmxi
-                    
+
                     Am = (obj.Aevaluated-alphaA*I_N)/2;
-                    
+
                     obj.Aevaluated = [];
                     Dpxi = kr(I_n, ops_xi.Dp, I_eta,I_zeta);
                     temp = Am*Dpxi;
                     diffSum = diffSum-temp;
                     clear Am Dpxi
-                    
+
                     Bp = (obj.Bevaluated+alphaB*I_N)/2;
                     Dmeta = kr(I_n, I_xi, ops_eta.Dm,I_zeta);
                     temp = Bp*Dmeta;
                     diffSum = diffSum-temp;
                     clear Bp Dmeta
-                    
+
                     Bm = (obj.Bevaluated-alphaB*I_N)/2;
                     obj.Bevaluated = [];
                     Dpeta = kr(I_n, I_xi, ops_eta.Dp,I_zeta);
                     temp = Bm*Dpeta;
                     diffSum = diffSum-temp;
                     clear Bm Dpeta
-                    
+
                     Cp = (obj.Cevaluated+alphaC*I_N)/2;
                     Dmzeta = kr(I_n, I_xi, I_eta,ops_zeta.Dm);
                     temp = Cp*Dmzeta;
                     diffSum = diffSum-temp;
                     clear Cp Dmzeta
-                    
+
                     Cm = (obj.Cevaluated-alphaC*I_N)/2;
                     clear I_N
                     obj.Cevaluated = [];
@@ -179,72 +179,72 @@
                     temp = Cm*Dpzeta;
                     diffSum = diffSum-temp;
                     clear Cm Dpzeta temp
-                    
+
                     obj.J = obj.X_xi.*obj.Y_eta.*obj.Z_zeta...
                         +obj.X_zeta.*obj.Y_xi.*obj.Z_eta...
                         +obj.X_eta.*obj.Y_zeta.*obj.Z_xi...
                         -obj.X_xi.*obj.Y_zeta.*obj.Z_eta...
                         -obj.X_eta.*obj.Y_xi.*obj.Z_zeta...
                         -obj.X_zeta.*obj.Y_eta.*obj.Z_xi;
-                    
+
                     obj.Ji = kr(I_n,spdiags(1./obj.J,0,m_tot,m_tot));
                     obj.Eevaluated = obj.evaluateCoefficientMatrix(obj.E, obj.X, obj.Y,obj.Z,[],[],[],[],[],[]);
-                    
+
                     obj.D = obj.Ji*diffSum-obj.Eevaluated;
-                    
+
                 case 'standard'
                     D1_xi = kr(I_n,D1_xi);
                     D1_eta = kr(I_n,D1_eta);
                     D1_zeta = kr(I_n,D1_zeta);
-                    
+
                     obj.J = obj.X_xi.*obj.Y_eta.*obj.Z_zeta...
                         +obj.X_zeta.*obj.Y_xi.*obj.Z_eta...
                         +obj.X_eta.*obj.Y_zeta.*obj.Z_xi...
                         -obj.X_xi.*obj.Y_zeta.*obj.Z_eta...
                         -obj.X_eta.*obj.Y_xi.*obj.Z_zeta...
                         -obj.X_zeta.*obj.Y_eta.*obj.Z_xi;
-                    
+
                     obj.Ji = kr(I_n,spdiags(1./obj.J,0,m_tot,m_tot));
                     obj.Eevaluated = obj.evaluateCoefficientMatrix(obj.E, obj.X, obj.Y,obj.Z,[],[],[],[],[],[]);
-                    
+
                     obj.D = obj.Ji*(-obj.Aevaluated*D1_xi-obj.Bevaluated*D1_eta -obj.Cevaluated*D1_zeta)-obj.Eevaluated;
                 otherwise
                     error('Operator not supported')
             end
-            
+
             obj.Hxii = kr(I_n, ops_xi.HI, I_eta,I_zeta);
             obj.Hetai = kr(I_n, I_xi, ops_eta.HI,I_zeta);
             obj.Hzetai = kr(I_n, I_xi,I_eta, ops_zeta.HI);
-            
+
             obj.index_w = (kr(ops_xi.e_l, O_eta,O_zeta)==1);
             obj.index_e = (kr(ops_xi.e_r, O_eta,O_zeta)==1);
             obj.index_s = (kr(O_xi, ops_eta.e_l,O_zeta)==1);
             obj.index_n = (kr(O_xi, ops_eta.e_r,O_zeta)==1);
             obj.index_b = (kr(O_xi, O_eta, ops_zeta.e_l)==1);
             obj.index_t = (kr(O_xi, O_eta, ops_zeta.e_r)==1);
-            
+
             obj.e_w = kr(I_n, ops_xi.e_l, I_eta,I_zeta);
             obj.e_e = kr(I_n, ops_xi.e_r, I_eta,I_zeta);
             obj.e_s = kr(I_n, I_xi, ops_eta.e_l,I_zeta);
             obj.e_n = kr(I_n, I_xi, ops_eta.e_r,I_zeta);
             obj.e_b = kr(I_n, I_xi, I_eta, ops_zeta.e_l);
             obj.e_t = kr(I_n, I_xi, I_eta, ops_zeta.e_r);
-            
+
             obj.Eta_xi = kr(obj.eta,ones(m_xi,1));
             obj.Zeta_xi = kr(ones(m_eta,1),obj.zeta);
             obj.Xi_eta = kr(obj.xi,ones(m_zeta,1));
             obj.Zeta_eta = kr(ones(m_xi,1),obj.zeta);
             obj.Xi_zeta = kr(obj.xi,ones(m_eta,1));
-            obj.Eta_zeta = kr(ones(m_zeta,1),obj.eta);           
+            obj.Eta_zeta = kr(ones(m_zeta,1),obj.eta);
         end
-        
+
         function [ret] = transform_coefficient_matrix(obj,x,y,z,x_1,x_2,y_1,y_2,z_1,z_2)
             ret = obj.A(obj,x,y,z).*(y_1.*z_2-z_1.*y_2);
             ret = ret+obj.B(obj,x,y,z).*(x_2.*z_1-x_1.*z_2);
             ret = ret+obj.C(obj,x,y,z).*(x_1.*y_2-x_2.*y_1);
         end
-        
-        
+
+
         % Closure functions return the opertors applied to the own doamin to close the boundary
         % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
         %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
@@ -253,7 +253,7 @@
         function [closure, penalty] = boundary_condition(obj,boundary,type,L)
             default_arg('type','char');
             BM = boundary_matrices(obj,boundary);
-            
+
             switch type
                 case{'c','char'}
                     [closure,penalty] = boundary_condition_char(obj,BM);
@@ -263,15 +263,15 @@
                     error('No such boundary condition')
             end
         end
-        
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
-            error('An interface function does not exist yet');
+
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
+            error('Not implemented');
         end
-        
+
         function N = size(obj)
             N = obj.m;
         end
-        
+
         % Evaluates the symbolic Coeffiecient matrix mat
         function [ret] = evaluateCoefficientMatrix(obj,mat, X, Y, Z , x_1 , x_2 , y_1 , y_2 , z_1 , z_2)
             params = obj.params;
@@ -294,7 +294,7 @@
             end
             matVec(abs(matVec)<10^(-10)) = 0;
             ret = cell(rows,cols);
-            
+
             for ii = 1:rows
                 for jj = 1:cols
                     ret{ii,jj} = diag(matVec(ii,(jj-1)*side+1:jj*side));
@@ -302,7 +302,7 @@
             end
             ret = cell2mat(ret);
         end
-        
+
         function [BM] = boundary_matrices(obj,boundary)
             params = obj.params;
             BM.boundary = boundary;
@@ -385,7 +385,7 @@
             BM.side = sum(BM.index);
             BM.pos = signVec(1); BM.zeroval=signVec(2); BM.neg=signVec(3);
         end
-        
+
         % Characteristic boundary condition
         function [closure, penalty] = boundary_condition_char(obj,BM)
             side = BM.side;
@@ -397,7 +397,7 @@
             Hi = BM.Hi;
             D = BM.D;
             e_ = BM.e_;
-            
+
             switch BM.boundpos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -413,7 +413,7 @@
                     penalty = -Hi*e_*V*tau*Vi_minus;
             end
         end
-        
+
         % General boundary condition in the form Lu=g(x)
         function [closure,penalty] = boundary_condition_general(obj,BM,boundary,L)
             side = BM.side;
@@ -426,7 +426,7 @@
             D = BM.D;
             e_ = BM.e_;
             index = BM.index;
-            
+
             switch BM.boundary
                 case{'b','B','bottom'}
                     Ji_vec = diag(obj.Ji);
@@ -434,10 +434,10 @@
                     Zeta_x = Ji*(obj.Y_xi(index).*obj.Z_eta(index)-obj.Z_xi(index).*obj.Y_eta(index));
                     Zeta_y = Ji*(obj.X_eta(index).*obj.Z_xi(index)-obj.X_xi(index).*obj.Z_eta(index));
                     Zeta_z = Ji*(obj.X_xi(index).*obj.Y_eta(index)-obj.Y_xi(index).*obj.X_eta(index));
-                    
+
                     L = obj.evaluateCoefficientMatrix(L,Zeta_x,Zeta_y,Zeta_z,[],[],[],[],[],[]);
             end
-            
+
             switch BM.boundpos
                 case {'l'}
                     tau = sparse(obj.n*side,pos);
@@ -445,7 +445,7 @@
                     Vi_minus = Vi(pos+zeroval+1:obj.n*side,:);
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos+zeroval)+1:obj.n*side);
-                    
+
                     tau(1:pos,:) = -abs(D(1:pos,1:pos));
                     R = -inv(L*V_plus)*(L*V_minus);
                     closure = Hi*e_*V*tau*(Vi_plus-R*Vi_minus)*e_';
@@ -455,7 +455,7 @@
                     tau((pos+zeroval)+1:obj.n*side,:) = -abs(D((pos+zeroval)+1:obj.n*side,(pos+zeroval)+1:obj.n*side));
                     Vi_plus = Vi(1:pos,:);
                     Vi_minus = Vi((pos+zeroval)+1:obj.n*side,:);
-                    
+
                     V_plus = V(:,1:pos);
                     V_minus = V(:,(pos+zeroval)+1:obj.n*side);
                     R = -inv(L*V_minus)*(L*V_plus);
@@ -463,7 +463,7 @@
                     penalty = -Hi*e_*V*tau*inv(L*V_minus)*L;
             end
         end
-        
+
         % Function that diagonalizes a symbolic matrix A as A=V*D*Vi
         % D         is a diagonal matrix with the eigenvalues on A on the diagonal sorted by their sign
         %                                    [d+       ]
@@ -478,38 +478,38 @@
             else
                 x_1s = 0;
             end
-            
+
             if(sum(abs(x_2))>eps)
                 syms x_2s;
             else
                 x_2s = 0;
             end
-            
-            
+
+
             if(sum(abs(y_1))>eps)
                 syms y_1s
             else
                 y_1s = 0;
             end
-            
+
             if(sum(abs(y_2))>eps)
                 syms y_2s;
             else
                 y_2s = 0;
             end
-            
+
             if(sum(abs(z_1))>eps)
                 syms z_1s
             else
                 z_1s = 0;
             end
-            
+
             if(sum(abs(z_2))>eps)
                 syms z_2s;
             else
                 z_2s = 0;
             end
-            
+
             syms xs ys zs
             [V, D] = eig(mat(obj,xs,ys,zs,x_1s,x_2s,y_1s,y_2s,z_1s,z_2s));
             Vi = inv(V);
@@ -522,12 +522,12 @@
             y_2s = y_2;
             z_1s = z_1;
             z_2s = z_2;
-            
+
             side = max(length(x),length(y));
             Dret = zeros(obj.n,side*obj.n);
             Vret = zeros(obj.n,side*obj.n);
             Viret = zeros(obj.n,side*obj.n);
-            
+
             for ii=1:obj.n
                 for jj=1:obj.n
                     Dret(jj,(ii-1)*side+1:side*ii) = eval(D(jj,ii));
@@ -535,7 +535,7 @@
                     Viret(jj,(ii-1)*side+1:side*ii) = eval(Vi(jj,ii));
                 end
             end
-            
+
             D = sparse(Dret);
             V = sparse(Vret);
             Vi = sparse(Viret);
@@ -543,11 +543,11 @@
             D = obj.evaluateCoefficientMatrix(D,x,y,z,x_1,x_2,y_1,y_2,z_1,z_2);
             Vi = obj.evaluateCoefficientMatrix(Vi,x,y,z,x_1,x_2,y_1,y_2,z_1,z_2);
             DD = diag(D);
-            
+
             poseig = (DD>0);
             zeroeig = (DD==0);
             negeig = (DD<0);
-            
+
             D = diag([DD(poseig); DD(zeroeig); DD(negeig)]);
             V = [V(:,poseig) V(:,zeroeig) V(:,negeig)];
             Vi = [Vi(poseig,:); Vi(zeroeig,:); Vi(negeig,:)];
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+scheme/Laplace1d.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,158 @@
+classdef Laplace1d < scheme.Scheme
+    properties
+        grid
+        order % Order accuracy for the approximation
+
+        D % non-stabalized scheme operator
+        H % Discrete norm
+        M % Derivative norm
+        a
+
+        D2
+        Hi
+        e_l
+        e_r
+        d_l
+        d_r
+        gamm
+    end
+
+    methods
+        function obj = Laplace1d(grid, order, a)
+            default_arg('a', 1);
+
+            assertType(grid, 'grid.Cartesian');
+
+            ops = sbp.D2Standard(grid.size(), grid.lim{1}, order);
+
+            obj.D2 = sparse(ops.D2);
+            obj.H =  sparse(ops.H);
+            obj.Hi = sparse(ops.HI);
+            obj.M =  sparse(ops.M);
+            obj.e_l = sparse(ops.e_l);
+            obj.e_r = sparse(ops.e_r);
+            obj.d_l = -sparse(ops.d1_l);
+            obj.d_r = sparse(ops.d1_r);
+
+
+            obj.grid = grid;
+            obj.order = order;
+
+            obj.a = a;
+            obj.D = a*obj.D2;
+
+            obj.gamm = grid.h*ops.borrowing.M.S;
+        end
+
+
+        % Closure functions return the opertors applied to the own doamin to close the boundary
+        % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
+        %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
+        %       type                is a string specifying the type of boundary condition if there are several.
+        %       data                is a function returning the data that should be applied at the boundary.
+        %       neighbour_scheme    is an instance of Scheme that should be interfaced to.
+        %       neighbour_boundary  is a string specifying which boundary to interface to.
+        function [closure, penalty] = boundary_condition(obj,boundary,type,data)
+            default_arg('type','neumann');
+            default_arg('data',0);
+
+            e = obj.getBoundaryOperator('e', boundary);
+            d = obj.getBoundaryOperator('d', boundary);
+            s = obj.getBoundarySign(boundary);
+
+            switch type
+                % Dirichlet boundary condition
+                case {'D','dirichlet'}
+                    tuning = 1.1;
+                    tau1 = -tuning/obj.gamm;
+                    tau2 =  1;
+
+                    tau = tau1*e + tau2*d;
+
+                    closure = obj.a*obj.Hi*tau*e';
+                    penalty = obj.a*obj.Hi*tau;
+
+                % Neumann boundary condition
+                case {'N','neumann'}
+                    tau = -e;
+
+                    closure = obj.a*obj.Hi*tau*d';
+                    penalty = -obj.a*obj.Hi*tau;
+
+                % Unknown, boundary condition
+                otherwise
+                    error('No such boundary condition: type = %s',type);
+            end
+        end
+
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
+            % u denotes the solution in the own domain
+            % v denotes the solution in the neighbour domain
+            e_u = obj.getBoundaryOperator('e', boundary);
+            d_u = obj.getBoundaryOperator('d', boundary);
+            s_u = obj.getBoundarySign(boundary);
+
+            e_v = neighbour_scheme.getBoundaryOperator('e', neighbour_boundary);
+            d_v = neighbour_scheme.getBoundaryOperator('d', neighbour_boundary);
+            s_v = neighbour_scheme.getBoundarySign(neighbour_boundary);
+
+            a_u = obj.a;
+            a_v = neighbour_scheme.a;
+
+            gamm_u = obj.gamm;
+            gamm_v = neighbour_scheme.gamm;
+
+            tuning = 1.1;
+
+            tau1 = -(a_u/gamm_u + a_v/gamm_v) * tuning;
+            tau2 = 1/2*a_u;
+            sig1 = -1/2;
+            sig2 = 0;
+
+            tau = tau1*e_u + tau2*d_u;
+            sig = sig1*e_u + sig2*d_u;
+
+            closure = obj.Hi*( tau*e_u' + sig*a_u*d_u');
+            penalty = obj.Hi*(-tau*e_v' + sig*a_v*d_v');
+        end
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string
+        % boundary  -- string
+        function o = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(op, {'e', 'd'})
+            assertIsMember(boundary, {'l', 'r'})
+
+            o = obj.([op, '_', boundary])
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        % Note: for 1d diffOps, the boundary quadrature is the scalar 1.
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
+            H_b = 1;
+        end
+
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
+            switch boundary
+                case {'r'}
+                    s = 1;
+                case {'l'}
+                    s = -1;
+            end
+        end
+
+        function N = size(obj)
+            N = obj.grid.size();
+        end
+
+    end
+end
--- a/+scheme/LaplaceCurvilinear.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/LaplaceCurvilinear.m	Tue Feb 12 17:12:42 2019 +0100
@@ -38,6 +38,7 @@
         du_n, dv_n
         gamm_u, gamm_v
         lambda
+
     end
 
     methods
@@ -53,7 +54,11 @@
                 error('Not implemented yet')
             end
 
-            assert(isa(g, 'grid.Curvilinear'))
+            % assert(isa(g, 'grid.Curvilinear'))
+            if isa(a, 'function_handle')
+                a = grid.evalOn(g, a);
+                a = spdiag(a);
+            end
 
             m = g.size();
             m_u = m(1);
@@ -233,7 +238,10 @@
             default_arg('type','neumann');
             default_arg('parameter', []);
 
-            [e, d, gamm, H_b, ~] = obj.get_boundary_ops(boundary);
+            e = obj.getBoundaryOperator('e', boundary);
+            d = obj.getBoundaryOperator('d', boundary);
+            H_b = obj.getBoundaryQuadrature(boundary);
+            gamm = obj.getBoundaryBorrowing(boundary);
             switch type
                 % Dirichlet boundary condition
                 case {'D','d','dirichlet'}
@@ -268,13 +276,42 @@
             end
         end
 
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
+        % type     Struct that specifies the interface coupling.
+        %          Fields:
+        %          -- tuning:           penalty strength, defaults to 1.2
+        %          -- interpolation:    type of interpolation, default 'none'
+        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+            defaultType.tuning = 1.2;
+            defaultType.interpolation = 'none';
+            default_struct('type', defaultType);
+
+            switch type.interpolation
+            case {'none', ''}
+                [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            case {'op','OP'}
+                [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            otherwise
+                error('Unknown type of interpolation: %s ', type.interpolation);
+            end
+        end
+
+        function [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+            tuning = type.tuning;
+
             % u denotes the solution in the own domain
             % v denotes the solution in the neighbour domain
-            tuning = 1.2;
-            % tuning = 20.2;
-            [e_u, d_u, gamm_u, H_b_u, I_u] = obj.get_boundary_ops(boundary);
-            [e_v, d_v, gamm_v, H_b_v, I_v] = neighbour_scheme.get_boundary_ops(neighbour_boundary);
+            e_u    = obj.getBoundaryOperator('e', boundary);
+            d_u    = obj.getBoundaryOperator('d', boundary);
+            H_b_u = obj.getBoundaryQuadrature(boundary);
+            I_u = obj.getBoundaryIndices(boundary);
+            gamm_u = obj.getBoundaryBorrowing(boundary);
+
+            e_v    = neighbour_scheme.getBoundaryOperator('e', neighbour_boundary);
+            d_v    = neighbour_scheme.getBoundaryOperator('d', neighbour_boundary);
+            H_b_v = neighbour_scheme.getBoundaryQuadrature(neighbour_boundary);
+            I_v = neighbour_scheme.getBoundaryIndices(neighbour_boundary);
+            gamm_v = neighbour_scheme.getBoundaryBorrowing(neighbour_boundary);
 
             u = obj;
             v = neighbour_scheme;
@@ -298,41 +335,113 @@
             penalty = obj.a*obj.Hi*(-tau*e_v' + sig*d_v');
         end
 
-        % Ruturns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
+        function [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+            % TODO: Make this work for curvilinear grids
+            warning('LaplaceCurvilinear: Non-conforming grid interpolation only works for Cartesian grids.');
+
+            % User can request special interpolation operators by specifying type.interpOpSet
+            default_field(type, 'interpOpSet', @sbp.InterpOpsOP);
+            interpOpSet = type.interpOpSet;
+            tuning = type.tuning;
+
+
+            % u denotes the solution in the own domain
+            % v denotes the solution in the neighbour domain
+            e_u    = obj.getBoundaryOperator('e', boundary);
+            d_u    = obj.getBoundaryOperator('d', boundary);
+            H_b_u  = obj.getBoundaryQuadrature(boundary);
+            I_u    = obj.getBoundaryIndices(boundary);
+            gamm_u = obj.getBoundaryBorrowing(boundary);
+
+            e_v    = neighbour_scheme.getBoundaryOperator('e', neighbour_boundary);
+            d_v    = neighbour_scheme.getBoundaryOperator('d', neighbour_boundary);
+            H_b_v  = neighbour_scheme.getBoundaryQuadrature(neighbour_boundary);
+            I_v    = neighbour_scheme.getBoundaryIndices(neighbour_boundary);
+            gamm_v = neighbour_scheme.getBoundaryBorrowing(neighbour_boundary);
+
+
+            % Find the number of grid points along the interface
+            m_u = size(e_u, 2);
+            m_v = size(e_v, 2);
+
+            Hi = obj.Hi;
+            a = obj.a;
+
+            u = obj;
+            v = neighbour_scheme;
+
+            b1_u = gamm_u*u.lambda(I_u)./u.a11(I_u).^2;
+            b2_u = gamm_u*u.lambda(I_u)./u.a22(I_u).^2;
+            b1_v = gamm_v*v.lambda(I_v)./v.a11(I_v).^2;
+            b2_v = gamm_v*v.lambda(I_v)./v.a22(I_v).^2;
+
+            tau_u = -1./(4*b1_u) -1./(4*b2_u);
+            tau_v = -1./(4*b1_v) -1./(4*b2_v);
+
+            tau_u = tuning * spdiag(tau_u);
+            tau_v = tuning * spdiag(tau_v);
+            beta_u = tau_v;
+
+            % Build interpolation operators
+            intOps = interpOpSet(m_u, m_v, obj.order, neighbour_scheme.order);
+            Iu2v = intOps.Iu2v;
+            Iv2u = intOps.Iv2u;
+
+            closure = a*Hi*e_u*tau_u*H_b_u*e_u' + ...
+                      a*Hi*e_u*H_b_u*Iv2u.bad*beta_u*Iu2v.good*e_u' + ...
+                      a*1/2*Hi*d_u*H_b_u*e_u' + ...
+                      -a*1/2*Hi*e_u*H_b_u*d_u';
+
+            penalty = -a*Hi*e_u*tau_u*H_b_u*Iv2u.good*e_v' + ...
+                      -a*Hi*e_u*H_b_u*Iv2u.bad*beta_u*e_v' + ...
+                      -a*1/2*Hi*d_u*H_b_u*Iv2u.good*e_v' + ...
+                      -a*1/2*Hi*e_u*H_b_u*Iv2u.bad*d_v';
+
+        end
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string
+        % boundary  -- string
+        function o = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(op, {'e', 'd'})
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            o = obj.([op, '_', boundary]);
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
         %
-        %  I -- the indecies of the boundary points in the grid matrix
-        function [e, d, gamm, H_b, I] = get_boundary_ops(obj, boundary)
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
-            % gridMatrix = zeros(obj.m(2),obj.m(1));
-            % gridMatrix(:) = 1:numel(gridMatrix);
+            H_b = obj.(['H_', boundary]);
+        end
+
+        % Returns the indices of the boundary points in the grid matrix
+        % boundary -- string
+        function I = getBoundaryIndices(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
             ind = grid.funcToMatrix(obj.grid, 1:prod(obj.m));
-
             switch boundary
                 case 'w'
-                    e = obj.e_w;
-                    d = obj.d_w;
-                    H_b = obj.H_w;
                     I = ind(1,:);
                 case 'e'
-                    e = obj.e_e;
-                    d = obj.d_e;
-                    H_b = obj.H_e;
                     I = ind(end,:);
                 case 's'
-                    e = obj.e_s;
-                    d = obj.d_s;
-                    H_b = obj.H_s;
                     I = ind(:,1)';
                 case 'n'
-                    e = obj.e_n;
-                    d = obj.d_n;
-                    H_b = obj.H_n;
                     I = ind(:,end)';
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
             end
+        end
+
+        % Returns borrowing constant gamma
+        % boundary -- string
+        function gamm = getBoundaryBorrowing(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
 
             switch boundary
                 case {'w','e'}
--- a/+scheme/Scheme.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Scheme.m	Tue Feb 12 17:12:42 2019 +0100
@@ -26,22 +26,15 @@
         %                           interface to.
         %       penalty  may be a cell array if there are several penalties with different weights
         [closure, penalty] = boundary_condition(obj,boundary,type) % TODO: Change name to boundaryCondition
-        [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
 
-        % TODO: op = getBoundaryOperator()??
-        %   makes sense to have it available through a method instead of random properties
+        % type -- sets the type of interface, could be a string or a struct or something else
+        %         depending on the particular scheme implementation
+        [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+        op = getBoundaryOperator(obj, opName, boundary)
+        H_b= getBoundaryQuadrature(obj, boundary)
 
         % Returns the number of degrees of freedom.
         N = size(obj)
     end
-
-    methods(Static)
-        % Calculates the matrcis need for the inteface coupling between
-        % boundary bound_u of scheme schm_u and bound_v of scheme schm_v.
-        %   [uu, uv, vv, vu] = inteface_coupling(A,'r',B,'l')
-        function [uu, uv, vv, vu] = interface_coupling(schm_u,bound_u,schm_v,bound_v)
-            [uu,uv] = schm_u.interface(bound_u,schm_v,bound_v);
-            [vv,vu] = schm_v.interface(bound_v,schm_u,bound_u);
-        end
-    end
 end
--- a/+scheme/Schrodinger.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Schrodinger.m	Tue Feb 12 17:12:42 2019 +0100
@@ -67,7 +67,8 @@
             default_arg('type','dirichlet');
             default_arg('data',0);
 
-            [e,d,s] = obj.get_boundary_ops(boundary);
+            [e, d] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            s = obj.getBoundarySign(boundary);
 
             switch type
                 % Dirichlet boundary condition
@@ -90,11 +91,14 @@
             end
         end
 
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
             % u denotes the solution in the own domain
             % v denotes the solution in the neighbour domain
-            [e_u,d_u,s_u] = obj.get_boundary_ops(boundary);
-            [e_v,d_v,s_v] = neighbour_scheme.get_boundary_ops(neighbour_boundary);
+            [e_u, d_u] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            s_u = obj.getBoundarySign(boundary);
+
+            [e_v, d_v] = neighbour_scheme.getBoundaryOperator({'e', 'd'}, neighbour_boundary);
+            s_v = neighbour_scheme.getBoundarySign(neighbour_boundary);
 
             a =  -s_u* 1/2 * 1i ;
             b =  a';
@@ -106,20 +110,60 @@
             penalty = obj.Hi * (-tau*e_v' - sig*d_v');
         end
 
-        % Ruturns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
-        function [e,d,s] = get_boundary_ops(obj,boundary)
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
+            if ~iscell(op)
+                op = {op};
+            end
+
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'l'
+                        e = obj.e_l;
+                    case 'r'
+                        e = obj.e_r;
+                    end
+                    varargout{i} = e;
+
+                case 'd'
+                    switch boundary
+                    case 'l'
+                        d = obj.d1_l;
+                    case 'r'
+                        d = obj.d1_r;
+                    end
+                    varargout{i} = d;
+                end
+            end
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        % Note: for 1d diffOps, the boundary quadrature is the scalar 1.
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
+            H_b = 1;
+        end
+
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
             switch boundary
-                case 'l'
-                    e = obj.e_l;
-                    d = obj.d1_l;
+                case {'r'}
+                    s = 1;
+                case {'l'}
                     s = -1;
-                case 'r'
-                    e = obj.e_r;
-                    d = obj.d1_r;
-                    s = 1;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
             end
         end
 
@@ -128,14 +172,4 @@
         end
 
     end
-
-    methods(Static)
-        % Calculates the matrcis need for the inteface coupling between boundary bound_u of scheme schm_u
-        % and bound_v of scheme schm_v.
-        %   [uu, uv, vv, vu] = inteface_couplong(A,'r',B,'l')
-        function [uu, uv, vv, vu] = interface_coupling(schm_u,bound_u,schm_v,bound_v)
-            [uu,uv] = schm_u.interface(bound_u,schm_v,bound_v);
-            [vv,vu] = schm_v.interface(bound_v,schm_u,bound_u);
-        end
-    end
-end
\ No newline at end of file
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+scheme/Schrodinger2d.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,366 @@
+classdef Schrodinger2d < scheme.Scheme
+
+% Discretizes the Laplacian with constant coefficent,
+% in the Schrödinger equation way (i.e., the discretization matrix is not necessarily
+% definite)
+% u_t = a*i*Laplace u
+% opSet should be cell array of opSets, one per dimension. This
+% is useful if we have periodic BC in one direction.
+
+    properties
+        m % Number of points in each direction, possibly a vector
+        h % Grid spacing
+
+        grid
+        dim
+
+        order % Order of accuracy for the approximation
+
+        % Diagonal matrix for variable coefficients
+        a % Constant coefficient
+
+        D % Total operator
+        D1 % First derivatives
+
+        % Second derivatives
+        D2
+
+        H, Hi % Inner products
+        e_l, e_r
+        d1_l, d1_r % Normal derivatives at the boundary
+        e_w, e_e, e_s, e_n
+        d_w, d_e, d_s, d_n
+
+        H_boundary % Boundary inner products
+
+    end
+
+    methods
+
+        function obj = Schrodinger2d(g ,order, a, opSet)
+            default_arg('opSet',{@sbp.D2Variable, @sbp.D2Variable});
+            default_arg('a',1);
+            dim = 2;
+
+            assertType(g, 'grid.Cartesian');
+            if isa(a, 'function_handle')
+                a = grid.evalOn(g, a);
+                a = spdiag(a);
+            end
+
+            m = g.size();
+            m_tot = g.N();
+
+            h = g.scaling();
+            xlim = {g.x{1}(1), g.x{1}(end)};
+            ylim = {g.x{2}(1), g.x{2}(end)};
+            lim = {xlim, ylim};
+
+            % 1D operators
+            ops = cell(dim,1);
+            for i = 1:dim
+                ops{i} = opSet{i}(m(i), lim{i}, order);
+            end
+
+            I = cell(dim,1);
+            D1 = cell(dim,1);
+            D2 = cell(dim,1);
+            H = cell(dim,1);
+            Hi = cell(dim,1);
+            e_l = cell(dim,1);
+            e_r = cell(dim,1);
+            d1_l = cell(dim,1);
+            d1_r = cell(dim,1);
+
+            for i = 1:dim
+                I{i} = speye(m(i));
+                D1{i} = ops{i}.D1;
+                D2{i} = ops{i}.D2;
+                H{i} =  ops{i}.H;
+                Hi{i} = ops{i}.HI;
+                e_l{i} = ops{i}.e_l;
+                e_r{i} = ops{i}.e_r;
+                d1_l{i} = ops{i}.d1_l;
+                d1_r{i} = ops{i}.d1_r;
+            end
+
+            % Constant coeff D2
+            for i = 1:dim
+                D2{i} = D2{i}(ones(m(i),1));
+            end
+
+            %====== Assemble full operators ========
+            obj.D1 = cell(dim,1);
+            obj.D2 = cell(dim,1);
+            obj.e_l = cell(dim,1);
+            obj.e_r = cell(dim,1);
+            obj.d1_l = cell(dim,1);
+            obj.d1_r = cell(dim,1);
+
+            % D1
+            obj.D1{1} = kron(D1{1},I{2});
+            obj.D1{2} = kron(I{1},D1{2});
+
+            % Boundary operators
+            obj.e_l{1} = kron(e_l{1},I{2});
+            obj.e_l{2} = kron(I{1},e_l{2});
+            obj.e_r{1} = kron(e_r{1},I{2});
+            obj.e_r{2} = kron(I{1},e_r{2});
+
+            obj.d1_l{1} = kron(d1_l{1},I{2});
+            obj.d1_l{2} = kron(I{1},d1_l{2});
+            obj.d1_r{1} = kron(d1_r{1},I{2});
+            obj.d1_r{2} = kron(I{1},d1_r{2});
+
+            % D2
+            obj.D2{1} = kron(D2{1},I{2});
+            obj.D2{2} = kron(I{1},D2{2});
+
+            % Quadratures
+            obj.H = kron(H{1},H{2});
+            obj.Hi = inv(obj.H);
+            obj.H_boundary = cell(dim,1);
+            obj.H_boundary{1} = H{2};
+            obj.H_boundary{2} = H{1};
+
+            % Differentiation matrix D (without SAT)
+            D2 = obj.D2;
+            D = sparse(m_tot,m_tot);
+            for j = 1:dim
+                D = D + a*1i*D2{j};
+            end
+            obj.D = D;
+            %=========================================%
+
+            % Misc.
+            obj.m = m;
+            obj.h = h;
+            obj.order = order;
+            obj.grid = g;
+            obj.dim = dim;
+            obj.a = a;
+            obj.e_w = obj.e_l{1};
+            obj.e_e = obj.e_r{1};
+            obj.e_s = obj.e_l{2};
+            obj.e_n = obj.e_r{2};
+            obj.d_w = obj.d1_l{1};
+            obj.d_e = obj.d1_r{1};
+            obj.d_s = obj.d1_l{2};
+            obj.d_n = obj.d1_r{2};
+
+        end
+
+
+        % Closure functions return the operators applied to the own domain to close the boundary
+        % Penalty functions return the operators to force the solution. In the case of an interface it returns the operator applied to the other doamin.
+        %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
+        %       type                is a string specifying the type of boundary condition.
+        %       data                is a function returning the data that should be applied at the boundary.
+        %       neighbour_scheme    is an instance of Scheme that should be interfaced to.
+        %       neighbour_boundary  is a string specifying which boundary to interface to.
+        function [closure, penalty] = boundary_condition(obj, boundary, type, parameter)
+            default_arg('type','Neumann');
+            default_arg('parameter', []);
+
+            % nj: outward unit normal component.
+            % nj = -1 for west, south, bottom boundaries
+            % nj = 1  for east, north, top boundaries
+            nj = obj.getBoundarySign(boundary);
+            [e, d] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            H_gamma = obj.getBoundaryQuadrature(boundary);
+            Hi = obj.Hi;
+            a = e'*obj.a*e;
+
+            switch type
+
+            % Dirichlet boundary condition
+            case {'D','d','dirichlet','Dirichlet'}
+                    closure =  nj*Hi*d*a*1i*H_gamma*(e' );
+                    penalty = -nj*Hi*d*a*1i*H_gamma;
+
+            % Free boundary condition
+            case {'N','n','neumann','Neumann'}
+                    closure = -nj*Hi*e*a*1i*H_gamma*(d' );
+                    penalty =  nj*Hi*e*a*1i*H_gamma;
+
+            % Unknown boundary condition
+            otherwise
+                error('No such boundary condition: type = %s',type);
+            end
+        end
+
+        % type     Struct that specifies the interface coupling.
+        %          Fields:
+        %          -- interpolation:    type of interpolation, default 'none'
+        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+            defaultType.interpolation = 'none';
+            default_struct('type', defaultType);
+
+            switch type.interpolation
+            case {'none', ''}
+                [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            case {'op','OP'}
+                [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            otherwise
+                error('Unknown type of interpolation: %s ', type.interpolation);
+            end
+        end
+
+        function [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+            % u denotes the solution in the own domain
+            % v denotes the solution in the neighbour domain
+
+            % Get boundary operators
+            [e_v, d_v] = neighbour_scheme.getBoundaryOperator({'e', 'd'}, neighbour_boundary);
+            [e_u, d_u] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            H_gamma = obj.getBoundaryQuadrature(boundary);
+            Hi = obj.Hi;
+            a = obj.a;
+
+            % Get outward unit normal component
+            n = obj.getBoundarySign(boundary);
+
+            Hi = obj.Hi;
+            sigma = -n*1i*a/2;
+            tau = -n*(1i*a)'/2;
+
+            closure = tau*Hi*d*H_gamma*e' + sigma*Hi*e*H_gamma*d';
+            penalty = -tau*Hi*d*H_gamma*e_neighbour' ...
+                      -sigma*Hi*e*H_gamma*d_neighbour';
+
+        end
+
+        function [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+            % User can request special interpolation operators by specifying type.interpOpSet
+            default_field(type, 'interpOpSet', @sbp.InterpOpsOP);
+            interpOpSet = type.interpOpSet;
+
+            % u denotes the solution in the own domain
+            % v denotes the solution in the neighbour domain
+            [e_v, d_v] = neighbour_scheme.getBoundaryOperator({'e', 'd'}, neighbour_boundary);
+            [e_u, d_u] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            H_gamma = obj.getBoundaryQuadrature(boundary);
+            Hi = obj.Hi;
+            a = obj.a;
+
+            % Get outward unit normal component
+            n = obj.getBoundarySign(boundary);
+
+            % Find the number of grid points along the interface
+            m_u = size(e_u, 2);
+            m_v = size(e_v, 2);
+
+            % Build interpolation operators
+            intOps = interpOpSet(m_u, m_v, obj.order, neighbour_scheme.order);
+            Iu2v = intOps.Iu2v;
+            Iv2u = intOps.Iv2u;
+
+            sigma = -n*1i*a/2;
+            tau = -n*(1i*a)'/2;
+
+            closure = tau*Hi*d_u*H_gamma*e_u' + sigma*Hi*e_u*H_gamma*d_u';
+            penalty = -tau*Hi*d_u*H_gamma*Iv2u.good*e_v' ...
+                      -sigma*Hi*e_u*H_gamma*Iv2u.bad*d_v';
+
+        end
+
+        % Returns the coordinate number and outward normal component for the boundary specified by the string boundary.
+        function [j, nj] = get_boundary_number(obj, boundary)
+
+            switch boundary
+                case {'w','W','west','West', 'e', 'E', 'east', 'East'}
+                    j = 1;
+                case {'s','S','south','South', 'n', 'N', 'north', 'North'}
+                    j = 2;
+                otherwise
+                    error('No such boundary: boundary = %s',boundary);
+            end
+
+            switch boundary
+                case {'w','W','west','West','s','S','south','South'}
+                    nj = -1;
+                case {'e', 'E', 'east', 'East','n', 'N', 'north', 'North'}
+                    nj = 1;
+            end
+        end
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            if ~iscell(op)
+                op = {op};
+            end
+
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'w'
+                        e = obj.e_w;
+                    case 'e'
+                        e = obj.e_e;
+                    case 's'
+                        e = obj.e_s;
+                    case 'n'
+                        e = obj.e_n;
+                    end
+                    varargout{i} = e;
+
+                case 'd'
+                    switch boundary
+                    case 'w'
+                        d = obj.d_w;
+                    case 'e'
+                        d = obj.d_e;
+                    case 's'
+                        d = obj.d_s;
+                    case 'n'
+                        d = obj.d_n;
+                    end
+                    varargout{i} = d;
+                end
+            end
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case 'w'
+                    H_b = obj.H_boundary{1};
+                case 'e'
+                    H_b = obj.H_boundary{1};
+                case 's'
+                    H_b = obj.H_boundary{2};
+                case 'n'
+                    H_b = obj.H_boundary{2};
+            end
+        end
+
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'e','n'}
+                    s = 1;
+                case {'w','s'}
+                    s = -1;
+            end
+        end
+
+        function N = size(obj)
+            N = prod(obj.m);
+        end
+    end
+end
--- a/+scheme/TODO.txt	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +0,0 @@
-% TODO: Rename package and abstract class to diffOp
--- a/+scheme/Utux.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Utux.m	Tue Feb 12 17:12:42 2019 +0100
@@ -2,7 +2,7 @@
    properties
         m % Number of points in each direction, possibly a vector
         h % Grid spacing
-        x % Grid
+        grid % Grid
         order % Order accuracy for the approximation
 
         H % Discrete norm
@@ -16,42 +16,30 @@
     end
 
 
-    methods 
-         function obj = Utux(m,xlim,order,operator)
-             default_arg('a',1);
-           
-           %Old operators  
-           % [x, h] = util.get_grid(xlim{:},m);
-           %ops = sbp.Ordinary(m,h,order);
-           
-           
-           switch operator
-               case 'NonEquidistant'
-              ops = sbp.D1Nonequidistant(m,xlim,order);
-              obj.D1 = ops.D1;
-               case 'Standard'
-              ops = sbp.D2Standard(m,xlim,order);
-              obj.D1 = ops.D1;
-               case 'Upwind'
-              ops = sbp.D1Upwind(m,xlim,order);
-              obj.D1 = ops.Dm;
-               otherwise
-                   error('Unvalid operator')
-           end
-              obj.x=ops.x;
+    methods
+        function obj = Utux(g, order, opSet)
+            default_arg('opSet',@sbp.D2Standard);
 
-            
+            m = g.size();
+            xl = g.getBoundary('l');
+            xr = g.getBoundary('r');
+            xlim = {xl, xr};
+
+            ops = opSet(m, xlim, order);
+            obj.D1 = ops.D1;
+
+            obj.grid = g;
+
             obj.H =  ops.H;
             obj.Hi = ops.HI;
-        
+
             obj.e_l = ops.e_l;
             obj.e_r = ops.e_r;
-            obj.D=obj.D1;
+            obj.D = -obj.D1;
 
             obj.m = m;
             obj.h = ops.h;
             obj.order = order;
-            obj.x = ops.x;
 
         end
         % Closure functions return the opertors applied to the own doamin to close the boundary
@@ -61,32 +49,53 @@
         %       data                is a function returning the data that should be applied at the boundary.
         %       neighbour_scheme    is an instance of Scheme that should be interfaced to.
         %       neighbour_boundary  is a string specifying which boundary to interface to.
-        function [closure, penalty] = boundary_condition(obj,boundary,type,data)
-            default_arg('type','neumann');
-            default_arg('data',0);
-            tau =-1*obj.e_l;  
-            closure = obj.Hi*tau*obj.e_l';       
-            penalty = 0*obj.e_l;
-                
+        function [closure, penalty] = boundary_condition(obj,boundary,type)
+            default_arg('type','dirichlet');
+            tau =-1*obj.e_l;
+            closure = obj.Hi*tau*obj.e_l';
+            penalty = -obj.Hi*tau;
+
+         end
+
+         function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
+             switch boundary
+                 % Upwind coupling
+                 case {'l','left'}
+                     tau = -1*obj.e_l;
+                     closure = obj.Hi*tau*obj.e_l';
+                     penalty = -obj.Hi*tau*neighbour_scheme.e_r';
+                 case {'r','right'}
+                     tau = 0*obj.e_r;
+                     closure = obj.Hi*tau*obj.e_r';
+                     penalty = -obj.Hi*tau*neighbour_scheme.e_l';
+             end
+
          end
-          
-         function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
-          error('An interface function does not exist yet');
-         end
-      
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string
+        % boundary  -- string
+        function o = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(op, {'e'})
+            assertIsMember(boundary, {'l', 'r'})
+
+            o = obj.([op, '_', boundary]);
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        % Note: for 1d diffOps, the boundary quadrature is the scalar 1.
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'l', 'r'})
+
+            H_b = 1;
+        end
+
         function N = size(obj)
             N = obj.m;
         end
 
     end
-
-    methods(Static)
-        % Calculates the matrcis need for the inteface coupling between boundary bound_u of scheme schm_u
-        % and bound_v of scheme schm_v.
-        %   [uu, uv, vv, vu] = inteface_couplong(A,'r',B,'l')
-        function [uu, uv, vv, vu] = interface_coupling(schm_u,bound_u,schm_v,bound_v)
-            [uu,uv] = schm_u.interface(bound_u,schm_v,bound_v);
-            [vv,vu] = schm_v.interface(bound_v,schm_u,bound_u);
-        end
-    end
-end
\ No newline at end of file
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+scheme/Utux2d.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,305 @@
+classdef Utux2d < scheme.Scheme
+   properties
+        m % Number of points in each direction, possibly a vector
+        h % Grid spacing
+        grid % Grid
+        order % Order accuracy for the approximation
+        v0 % Initial data
+
+        a % Wave speed a = [a1, a2];
+          % Can either be a constant vector or a cell array of function handles.
+
+        H % Discrete norm
+        H_x, H_y % Norms in the x and y directions
+        Hi, Hx, Hy, Hxi, Hyi % Kroneckered norms
+        H_w, H_e, H_s, H_n % Boundary quadratures
+
+        % Derivatives
+        Dx, Dy
+
+        % Boundary operators
+        e_w, e_e, e_s, e_n
+
+        D % Total discrete operator
+    end
+
+
+    methods
+         function obj = Utux2d(g ,order, opSet, a)
+
+            default_arg('a',1/sqrt(2)*[1, 1]);
+            default_arg('opSet',@sbp.D2Standard);
+
+            assertType(g, 'grid.Cartesian');
+            if iscell(a)
+                a1 = grid.evalOn(g, a{1});
+                a2 = grid.evalOn(g, a{2});
+                a = {spdiag(a1), spdiag(a2)};
+            else
+                a = {a(1), a(2)};
+            end
+
+            m = g.size();
+            m_x = m(1);
+            m_y = m(2);
+            m_tot = g.N();
+
+            xlim = {g.x{1}(1), g.x{1}(end)};
+            ylim = {g.x{2}(1), g.x{2}(end)};
+            obj.grid = g;
+
+            % Operator sets
+            ops_x = opSet(m_x, xlim, order);
+            ops_y = opSet(m_y, ylim, order);
+            Ix = speye(m_x);
+            Iy = speye(m_y);
+
+            % Norms
+            Hx = ops_x.H;
+            Hy = ops_y.H;
+            Hxi = ops_x.HI;
+            Hyi = ops_y.HI;
+
+            obj.H_w = Hy;
+            obj.H_e = Hy;
+            obj.H_s = Hx;
+            obj.H_n = Hx;
+            obj.H_x = Hx;
+            obj.H_y = Hy;
+            obj.H = kron(Hx,Hy);
+            obj.Hi = kron(Hxi,Hyi);
+            obj.Hx = kron(Hx,Iy);
+            obj.Hy = kron(Ix,Hy);
+            obj.Hxi = kron(Hxi,Iy);
+            obj.Hyi = kron(Ix,Hyi);
+
+            % Derivatives
+            Dx = ops_x.D1;
+            Dy = ops_y.D1;
+            obj.Dx = kron(Dx,Iy);
+            obj.Dy = kron(Ix,Dy);
+
+            % Boundary operators
+            obj.e_w = kr(ops_x.e_l, Iy);
+            obj.e_e = kr(ops_x.e_r, Iy);
+            obj.e_s = kr(Ix, ops_y.e_l);
+            obj.e_n = kr(Ix, ops_y.e_r);
+
+            obj.m = m;
+            obj.h = [ops_x.h ops_y.h];
+            obj.order = order;
+            obj.a = a;
+            obj.D = -(a{1}*obj.Dx + a{2}*obj.Dy);
+
+        end
+        % Closure functions return the opertors applied to the own domain to close the boundary
+        % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
+        %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
+        %       type                is a string specifying the type of boundary condition if there are several.
+        %       data                is a function returning the data that should be applied at the boundary.
+        %       neighbour_scheme    is an instance of Scheme that should be interfaced to.
+        %       neighbour_boundary  is a string specifying which boundary to interface to.
+        function [closure, penalty] = boundary_condition(obj,boundary,type)
+            default_arg('type','dirichlet');
+
+            sigma = -1; % Scalar penalty parameter
+            switch boundary
+                case {'w','W','west','West'}
+                    tau = sigma*obj.a{1}*obj.e_w*obj.H_y;
+                    closure = obj.Hi*tau*obj.e_w';
+
+                case {'s','S','south','South'}
+                    tau = sigma*obj.a{2}*obj.e_s*obj.H_x;
+                    closure = obj.Hi*tau*obj.e_s';
+            end
+            penalty = -obj.Hi*tau;
+
+        end
+
+        % type     Struct that specifies the interface coupling.
+        %          Fields:
+        %          -- couplingType             String, type of interface coupling
+        %                                       % Default: 'upwind'. Other: 'centered'
+        %          -- interpolation:    type of interpolation, default 'none'
+        %          -- interpolationDamping:    damping on upstream and downstream sides, when using interpolation.
+        %                                      Default {0,0} gives zero damping.
+        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+            defaultType.couplingType = 'upwind';
+            defaultType.interpolation = 'none';
+            defaultType.interpolationDamping = {0,0};
+            default_struct('type', defaultType);
+
+            switch type.interpolation
+            case {'none', ''}
+                [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            case {'op','OP'}
+                [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type);
+            otherwise
+                error('Unknown type of interpolation: %s ', type.interpolation);
+            end
+        end
+
+        function [closure, penalty] = interfaceStandard(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+            couplingType = type.couplingType;
+
+            % Get neighbour boundary operator
+            e_neighbour = neighbour_scheme.getBoundaryOperator('e', neighbour_boundary);
+
+            switch couplingType
+
+            % Upwind coupling (energy dissipation)
+            case 'upwind'
+                 sigma_ds = -1; %"Downstream" penalty
+                 sigma_us = 0; %"Upstream" penalty
+
+            % Energy-preserving coupling (no energy dissipation)
+            case 'centered'
+                 sigma_ds = -1/2; %"Downstream" penalty
+                 sigma_us = 1/2; %"Upstream" penalty
+
+            otherwise
+                error(['Interface coupling type ' couplingType ' is not available.'])
+            end
+
+            switch boundary
+                case {'w','W','west','West'}
+                    tau = sigma_ds*obj.a{1}*obj.e_w*obj.H_y;
+                    closure = obj.Hi*tau*obj.e_w';
+                    penalty = -obj.Hi*tau*e_neighbour';
+                case {'e','E','east','East'}
+                    tau = sigma_us*obj.a{1}*obj.e_e*obj.H_y;
+                    closure = obj.Hi*tau*obj.e_e';
+                    penalty = -obj.Hi*tau*e_neighbour';
+                case {'s','S','south','South'}
+                    tau = sigma_ds*obj.a{2}*obj.e_s*obj.H_x;
+                    closure = obj.Hi*tau*obj.e_s';
+                    penalty = -obj.Hi*tau*e_neighbour';
+                case {'n','N','north','North'}
+                    tau = sigma_us*obj.a{2}*obj.e_n*obj.H_x;
+                    closure = obj.Hi*tau*obj.e_n';
+                    penalty = -obj.Hi*tau*e_neighbour';
+             end
+
+         end
+
+         function [closure, penalty] = interfaceNonConforming(obj,boundary,neighbour_scheme,neighbour_boundary,type)
+
+            % User can request special interpolation operators by specifying type.interpOpSet
+            default_field(type, 'interpOpSet', @sbp.InterpOpsOP);
+
+            interpOpSet = type.interpOpSet;
+            couplingType = type.couplingType;
+            interpolationDamping = type.interpolationDamping;
+
+            % Get neighbour boundary operator
+            e_neighbour = neighbour_scheme.getBoundaryOperator('e', neighbour_boundary);
+
+            switch couplingType
+
+            % Upwind coupling (energy dissipation)
+            case 'upwind'
+                 sigma_ds = -1; %"Downstream" penalty
+                 sigma_us = 0; %"Upstream" penalty
+
+            % Energy-preserving coupling (no energy dissipation)
+            case 'centered'
+                 sigma_ds = -1/2; %"Downstream" penalty
+                 sigma_us = 1/2; %"Upstream" penalty
+
+            otherwise
+            error(['Interface coupling type ' couplingType ' is not available.'])
+            end
+
+            int_damp_us = interpolationDamping{1};
+            int_damp_ds = interpolationDamping{2};
+
+            % u denotes the solution in the own domain
+            % v denotes the solution in the neighbour domain
+            % Find the number of grid points along the interface
+            switch boundary
+                case {'w','e'}
+                    m_u = obj.m(2);
+                case {'s','n'}
+                    m_u = obj.m(1);
+            end
+            m_v = size(e_neighbour, 2);
+
+            % Build interpolation operators
+            intOps = interpOpSet(m_u, m_v, obj.order, neighbour_scheme.order);
+            Iu2v = intOps.Iu2v;
+            Iv2u = intOps.Iv2u;
+
+            I_local2neighbour_ds = intOps.Iu2v.bad;
+            I_local2neighbour_us = intOps.Iu2v.good;
+            I_neighbour2local_ds = intOps.Iv2u.good;
+            I_neighbour2local_us = intOps.Iv2u.bad;
+
+            I_back_forth_us = I_neighbour2local_us*I_local2neighbour_us;
+            I_back_forth_ds = I_neighbour2local_ds*I_local2neighbour_ds;
+
+
+            switch boundary
+            case {'w','W','west','West'}
+                tau = sigma_ds*obj.a{1}*obj.e_w*obj.H_y;
+                closure = obj.Hi*tau*obj.e_w';
+                penalty = -obj.Hi*tau*I_neighbour2local_ds*e_neighbour';
+
+                beta = int_damp_ds*obj.a{1}...
+                        *obj.e_w*obj.H_y;
+                closure = closure + obj.Hi*beta*I_back_forth_ds*obj.e_w' - obj.Hi*beta*obj.e_w';
+            case {'e','E','east','East'}
+                tau = sigma_us*obj.a{1}*obj.e_e*obj.H_y;
+                closure = obj.Hi*tau*obj.e_e';
+                penalty = -obj.Hi*tau*I_neighbour2local_us*e_neighbour';
+
+                beta = int_damp_us*obj.a{1}...
+                        *obj.e_e*obj.H_y;
+                closure = closure + obj.Hi*beta*I_back_forth_us*obj.e_e' - obj.Hi*beta*obj.e_e';
+            case {'s','S','south','South'}
+                tau = sigma_ds*obj.a{2}*obj.e_s*obj.H_x;
+                closure = obj.Hi*tau*obj.e_s';
+                penalty = -obj.Hi*tau*I_neighbour2local_ds*e_neighbour';
+
+                beta = int_damp_ds*obj.a{2}...
+                        *obj.e_s*obj.H_x;
+                closure = closure + obj.Hi*beta*I_back_forth_ds*obj.e_s' - obj.Hi*beta*obj.e_s';
+            case {'n','N','north','North'}
+                tau = sigma_us*obj.a{2}*obj.e_n*obj.H_x;
+                closure = obj.Hi*tau*obj.e_n';
+                penalty = -obj.Hi*tau*I_neighbour2local_us*e_neighbour';
+
+                beta = int_damp_us*obj.a{2}...
+                        *obj.e_n*obj.H_x;
+                closure = closure + obj.Hi*beta*I_back_forth_us*obj.e_n' - obj.Hi*beta*obj.e_n';
+             end
+
+
+         end
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string
+        % boundary  -- string
+        function o = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(op, {'e'})
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            o = obj.([op, '_', boundary]);
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            H_b = obj.(['H_', boundary]);
+        end
+
+        function N = size(obj)
+            N = obj.m;
+        end
+
+    end
+end
--- a/+scheme/Wave.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,175 +0,0 @@
-classdef Wave < scheme.Scheme
-    properties
-        m % Number of points in each direction, possibly a vector
-        h % Grid spacing
-        x % Grid
-        order % Order accuracy for the approximation
-
-        D % non-stabalized scheme operator
-        H % Discrete norm
-        M % Derivative norm
-        alpha
-
-        D2
-        Hi
-        e_l
-        e_r
-        d1_l
-        d1_r
-        gamm
-    end
-
-    methods
-        function obj = Wave(m,xlim,order,alpha)
-            default_arg('a',1);
-            [x, h] = util.get_grid(xlim{:},m);
-
-            ops = sbp.Ordinary(m,h,order);
-
-            obj.D2 = sparse(ops.derivatives.D2);
-            obj.H =  sparse(ops.norms.H);
-            obj.Hi = sparse(ops.norms.HI);
-            obj.M =  sparse(ops.norms.M);
-            obj.e_l = sparse(ops.boundary.e_1);
-            obj.e_r = sparse(ops.boundary.e_m);
-            obj.d1_l = sparse(ops.boundary.S_1);
-            obj.d1_r = sparse(ops.boundary.S_m);
-
-
-            obj.m = m;
-            obj.h = h;
-            obj.order = order;
-
-            obj.alpha = alpha;
-            obj.D = alpha*obj.D2;
-            obj.x = x;
-
-            obj.gamm = h*ops.borrowing.M.S;
-
-        end
-
-
-        % Closure functions return the opertors applied to the own doamin to close the boundary
-        % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
-        %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
-        %       type                is a string specifying the type of boundary condition if there are several.
-        %       data                is a function returning the data that should be applied at the boundary.
-        %       neighbour_scheme    is an instance of Scheme that should be interfaced to.
-        %       neighbour_boundary  is a string specifying which boundary to interface to.
-        function [closure, penalty] = boundary_condition(obj,boundary,type,data)
-            default_arg('type','neumann');
-            default_arg('data',0);
-
-            [e,d,s] = obj.get_boundary_ops(boundary);
-
-            switch type
-                % Dirichlet boundary condition
-                case {'D','dirichlet'}
-                    alpha = obj.alpha;
-
-                    % tau1 < -alpha^2/gamma
-                    tuning = 1.1;
-                    tau1 = -tuning*alpha/obj.gamm;
-                    tau2 =  s*alpha;
-
-                    p = tau1*e + tau2*d;
-
-                    closure = obj.Hi*p*e';
-
-                    pp = obj.Hi*p;
-                    switch class(data)
-                        case 'double'
-                            penalty = pp*data;
-                        case 'function_handle'
-                            penalty = @(t)pp*data(t);
-                        otherwise
-                            error('Wierd data argument!')
-                    end
-
-
-                % Neumann boundary condition
-                case {'N','neumann'}
-                    alpha = obj.alpha;
-                    tau1 = -s*alpha;
-                    tau2 = 0;
-                    tau = tau1*e + tau2*d;
-
-                    closure = obj.Hi*tau*d';
-
-                    pp = obj.Hi*tau;
-                    switch class(data)
-                        case 'double'
-                            penalty = pp*data;
-                        case 'function_handle'
-                            penalty = @(t)pp*data(t);
-                        otherwise
-                            error('Wierd data argument!')
-                    end
-
-                % Unknown, boundary condition
-                otherwise
-                    error('No such boundary condition: type = %s',type);
-            end
-        end
-
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
-            % u denotes the solution in the own domain
-            % v denotes the solution in the neighbour domain
-            [e_u,d_u,s_u] = obj.get_boundary_ops(boundary);
-            [e_v,d_v,s_v] = neighbour_scheme.get_boundary_ops(neighbour_boundary);
-
-            tuning = 1.1;
-
-            alpha_u = obj.alpha;
-            alpha_v = neighbour_scheme.alpha;
-
-            gamm_u = obj.gamm;
-            gamm_v = neighbour_scheme.gamm;
-
-            % tau1 < -(alpha_u/gamm_u + alpha_v/gamm_v)
-
-            tau1 = -(alpha_u/gamm_u + alpha_v/gamm_v) * tuning;
-            tau2 = s_u*1/2*alpha_u;
-            sig1 = s_u*(-1/2);
-            sig2 = 0;
-
-            tau = tau1*e_u + tau2*d_u;
-            sig = sig1*e_u + sig2*d_u;
-
-            closure = obj.Hi*( tau*e_u' + sig*alpha_u*d_u');
-            penalty = obj.Hi*(-tau*e_v' - sig*alpha_v*d_v');
-        end
-
-        % Ruturns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
-        function [e,d,s] = get_boundary_ops(obj,boundary)
-            switch boundary
-                case 'l'
-                    e = obj.e_l;
-                    d = obj.d1_l;
-                    s = -1;
-                case 'r'
-                    e = obj.e_r;
-                    d = obj.d1_r;
-                    s = 1;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
-            end
-        end
-
-        function N = size(obj)
-            N = obj.m;
-        end
-
-    end
-
-    methods(Static)
-        % Calculates the matrcis need for the inteface coupling between boundary bound_u of scheme schm_u
-        % and bound_v of scheme schm_v.
-        %   [uu, uv, vv, vu] = inteface_couplong(A,'r',B,'l')
-        function [uu, uv, vv, vu] = interface_coupling(schm_u,bound_u,schm_v,bound_v)
-            [uu,uv] = schm_u.interface(bound_u,schm_v,bound_v);
-            [vv,vu] = schm_v.interface(bound_v,schm_u,bound_u);
-        end
-    end
-end
\ No newline at end of file
--- a/+scheme/Wave2d.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/Wave2d.m	Tue Feb 12 17:12:42 2019 +0100
@@ -106,7 +106,10 @@
             default_arg('type','neumann');
             default_arg('data',0);
 
-            [e,d,s,gamm,halfnorm_inv] = obj.get_boundary_ops(boundary);
+            [e, d] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            gamm = obj.getBoundaryBorrowing(boundary);
+            s = obj.getBoundarySign(boundary);
+            halfnorm_inv = obj.getHalfnormInv(boundary);
 
             switch type
                 % Dirichlet boundary condition
@@ -158,12 +161,21 @@
             end
         end
 
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
+        function [closure, penalty] = interface(obj, boundary, neighbour_scheme, neighbour_boundary, type)
             % u denotes the solution in the own domain
             % v denotes the solution in the neighbour domain
             [e_u,d_u,s_u,gamm_u, halfnorm_inv] = obj.get_boundary_ops(boundary);
             [e_v,d_v,s_v,gamm_v] = neighbour_scheme.get_boundary_ops(neighbour_boundary);
 
+            [e_u, d_u] = obj.getBoundaryOperator({'e', 'd'}, boundary);
+            gamm_u = obj.getBoundaryBorrowing(boundary);
+            s_u = obj.getBoundarySign(boundary);
+            halfnorm_inv = obj.getHalfnormInv(boundary);
+
+            [e_v, d_v] = neighbour_scheme.getBoundaryOperator({'e', 'd'}, neighbour_boundary);
+            gamm_v = neighbour_scheme.getBoundaryBorrowing(neighbour_boundary);
+            s_v = neighbour_scheme.getBoundarySign(neighbour_boundary);
+
             tuning = 1.1;
 
             alpha_u = obj.alpha;
@@ -183,36 +195,107 @@
             penalty = halfnorm_inv*(-tau*e_v' - sig*alpha_v*d_v');
         end
 
-        % Ruturns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
-        function [e,d,s,gamm, halfnorm_inv] = get_boundary_ops(obj,boundary)
+
+        % Returns the boundary operator op for the boundary specified by the string boundary.
+        % op        -- string or a cell array of strings
+        % boundary  -- string
+        function varargout = getBoundaryOperator(obj, op, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            if ~iscell(op)
+                op = {op};
+            end
+
+            for i = 1:numel(op)
+                switch op{i}
+                case 'e'
+                    switch boundary
+                    case 'w'
+                        e = obj.e_w;
+                    case 'e'
+                        e = obj.e_e;
+                    case 's'
+                        e = obj.e_s;
+                    case 'n'
+                        e = obj.e_n;
+                    end
+                    varargout{i} = e;
+
+                case 'd'
+                    switch boundary
+                    case 'w'
+                        d = obj.d1_w;
+                    case 'e'
+                        d = obj.d1_e;
+                    case 's'
+                        d = obj.d1_s;
+                    case 'n'
+                        d = obj.d1_n;
+                    end
+                    varargout{i} = d;
+                end
+            end
+
+        end
+
+        % Returns square boundary quadrature matrix, of dimension
+        % corresponding to the number of boundary points
+        %
+        % boundary -- string
+        function H_b = getBoundaryQuadrature(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
             switch boundary
                 case 'w'
-                    e = obj.e_w;
-                    d = obj.d1_w;
-                    s = -1;
-                    gamm = obj.gamm_x;
-                    halfnorm_inv = obj.Hix;
+                    H_b = obj.H_y;
                 case 'e'
-                    e = obj.e_e;
-                    d = obj.d1_e;
-                    s = 1;
-                    gamm = obj.gamm_x;
-                    halfnorm_inv = obj.Hix;
+                    H_b = obj.H_y;
                 case 's'
-                    e = obj.e_s;
-                    d = obj.d1_s;
-                    s = -1;
-                    gamm = obj.gamm_y;
-                    halfnorm_inv = obj.Hiy;
+                    H_b = obj.H_x;
                 case 'n'
-                    e = obj.e_n;
-                    d = obj.d1_n;
-                    s = 1;
+                    H_b = obj.H_x;
+            end
+        end
+
+        % Returns borrowing constant gamma
+        % boundary -- string
+        function gamm = getBoundaryBorrowing(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'w','e'}
+                    gamm = obj.gamm_x;
+                case {'s','n'}
                     gamm = obj.gamm_y;
-                    halfnorm_inv = obj.Hiy;
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
+            end
+        end
+
+        % Returns the boundary sign. The right boundary is considered the positive boundary
+        % boundary -- string
+        function s = getBoundarySign(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case {'e','n'}
+                    s = 1;
+                case {'w','s'}
+                    s = -1;
+            end
+        end
+
+        % Returns the halfnorm_inv used in SATs. TODO: better notation
+        function Hinv = getHalfnormInv(obj, boundary)
+            assertIsMember(boundary, {'w', 'e', 's', 'n'})
+
+            switch boundary
+                case 'w'
+                    Hinv = obj.Hix;
+                case 'e'
+                    Hinv = obj.Hix;
+                case 's'
+                    Hinv = obj.Hiy;
+                case 'n'
+                    Hinv = obj.Hiy;
             end
         end
 
@@ -221,14 +304,4 @@
         end
 
     end
-
-    methods(Static)
-        % Calculates the matrcis need for the inteface coupling between boundary bound_u of scheme schm_u
-        % and bound_v of scheme schm_v.
-        %   [uu, uv, vv, vu] = inteface_couplong(A,'r',B,'l')
-        function [uu, uv, vv, vu] = interface_coupling(schm_u,bound_u,schm_v,bound_v)
-            [uu,uv] = schm_u.interface(bound_u,schm_v,bound_v);
-            [vv,vu] = schm_v.interface(bound_v,schm_u,bound_u);
-        end
-    end
-end
\ No newline at end of file
+end
--- a/+scheme/Wave2dCurve.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,359 +0,0 @@
-classdef Wave2dCurve < scheme.Scheme
-    properties
-        m % Number of points in each direction, possibly a vector
-        h % Grid spacing
-
-        grid
-
-        order % Order accuracy for the approximation
-
-        D % non-stabalized scheme operator
-        M % Derivative norm
-        c
-        J, Ji
-        a11, a12, a22
-
-        H % Discrete norm
-        Hi
-        H_u, H_v % Norms in the x and y directions
-        Hu,Hv % Kroneckerd norms. 1'*Hx*v corresponds to integration in the x dir.
-        Hi_u, Hi_v
-        Hiu, Hiv
-        e_w, e_e, e_s, e_n
-        du_w, dv_w
-        du_e, dv_e
-        du_s, dv_s
-        du_n, dv_n
-        gamm_u, gamm_v
-        lambda
-
-        Dx, Dy % Physical derivatives
-
-        x_u
-        x_v
-        y_u
-        y_v
-    end
-
-    methods
-        function obj = Wave2dCurve(g ,order, c, opSet)
-            default_arg('opSet',@sbp.D2Variable);
-            default_arg('c', 1);
-
-            warning('Use LaplaceCruveilinear instead')
-
-            assert(isa(g, 'grid.Curvilinear'))
-
-            m = g.size();
-            m_u = m(1);
-            m_v = m(2);
-            m_tot = g.N();
-
-            h = g.scaling();
-            h_u = h(1);
-            h_v = h(2);
-
-            % Operators
-            ops_u = opSet(m_u, {0, 1}, order);
-            ops_v = opSet(m_v, {0, 1}, order);
-
-            I_u = speye(m_u);
-            I_v = speye(m_v);
-
-            D1_u = ops_u.D1;
-            D2_u = ops_u.D2;
-            H_u =  ops_u.H;
-            Hi_u = ops_u.HI;
-            e_l_u = ops_u.e_l;
-            e_r_u = ops_u.e_r;
-            d1_l_u = ops_u.d1_l;
-            d1_r_u = ops_u.d1_r;
-
-            D1_v = ops_v.D1;
-            D2_v = ops_v.D2;
-            H_v =  ops_v.H;
-            Hi_v = ops_v.HI;
-            e_l_v = ops_v.e_l;
-            e_r_v = ops_v.e_r;
-            d1_l_v = ops_v.d1_l;
-            d1_r_v = ops_v.d1_r;
-
-            Du = kr(D1_u,I_v);
-            Dv = kr(I_u,D1_v);
-
-            % Metric derivatives
-            coords = g.points();
-            x = coords(:,1);
-            y = coords(:,2);
-
-            x_u = Du*x;
-            x_v = Dv*x;
-            y_u = Du*y;
-            y_v = Dv*y;
-
-            J = x_u.*y_v - x_v.*y_u;
-            a11 =  1./J .* (x_v.^2  + y_v.^2);
-            a12 = -1./J .* (x_u.*x_v + y_u.*y_v);
-            a22 =  1./J .* (x_u.^2  + y_u.^2);
-            lambda = 1/2 * (a11 + a22 - sqrt((a11-a22).^2 + 4*a12.^2));
-
-            % Assemble full operators
-            L_12 = spdiags(a12, 0, m_tot, m_tot);
-            Duv = Du*L_12*Dv;
-            Dvu = Dv*L_12*Du;
-
-            Duu = sparse(m_tot);
-            Dvv = sparse(m_tot);
-            ind = grid.funcToMatrix(g, 1:m_tot);
-
-            for i = 1:m_v
-                D = D2_u(a11(ind(:,i)));
-                p = ind(:,i);
-                Duu(p,p) = D;
-            end
-
-            for i = 1:m_u
-                D = D2_v(a22(ind(i,:)));
-                p = ind(i,:);
-                Dvv(p,p) = D;
-            end
-
-            obj.H = kr(H_u,H_v);
-            obj.Hi = kr(Hi_u,Hi_v);
-            obj.Hu  = kr(H_u,I_v);
-            obj.Hv  = kr(I_u,H_v);
-            obj.Hiu = kr(Hi_u,I_v);
-            obj.Hiv = kr(I_u,Hi_v);
-
-            obj.e_w  = kr(e_l_u,I_v);
-            obj.e_e  = kr(e_r_u,I_v);
-            obj.e_s  = kr(I_u,e_l_v);
-            obj.e_n  = kr(I_u,e_r_v);
-            obj.du_w = kr(d1_l_u,I_v);
-            obj.dv_w = (obj.e_w'*Dv)';
-            obj.du_e = kr(d1_r_u,I_v);
-            obj.dv_e = (obj.e_e'*Dv)';
-            obj.du_s = (obj.e_s'*Du)';
-            obj.dv_s = kr(I_u,d1_l_v);
-            obj.du_n = (obj.e_n'*Du)';
-            obj.dv_n = kr(I_u,d1_r_v);
-
-            obj.x_u = x_u;
-            obj.x_v = x_v;
-            obj.y_u = y_u;
-            obj.y_v = y_v;
-
-            obj.m = m;
-            obj.h = [h_u h_v];
-            obj.order = order;
-            obj.grid = g;
-
-            obj.c = c;
-            obj.J = spdiags(J, 0, m_tot, m_tot);
-            obj.Ji = spdiags(1./J, 0, m_tot, m_tot);
-            obj.a11 = a11;
-            obj.a12 = a12;
-            obj.a22 = a22;
-            obj.D = obj.Ji*c^2*(Duu + Duv + Dvu + Dvv);
-            obj.lambda = lambda;
-
-            obj.Dx = spdiag( y_v./J)*Du + spdiag(-y_u./J)*Dv;
-            obj.Dy = spdiag(-x_v./J)*Du + spdiag( x_u./J)*Dv;
-
-            obj.gamm_u = h_u*ops_u.borrowing.M.d1;
-            obj.gamm_v = h_v*ops_v.borrowing.M.d1;
-        end
-
-
-        % Closure functions return the opertors applied to the own doamin to close the boundary
-        % Penalty functions return the opertors to force the solution. In the case of an interface it returns the operator applied to the other doamin.
-        %       boundary            is a string specifying the boundary e.g. 'l','r' or 'e','w','n','s'.
-        %       type                is a string specifying the type of boundary condition if there are several.
-        %       data                is a function returning the data that should be applied at the boundary.
-        %       neighbour_scheme    is an instance of Scheme that should be interfaced to.
-        %       neighbour_boundary  is a string specifying which boundary to interface to.
-        function [closure, penalty] = boundary_condition(obj, boundary, type, parameter)
-            default_arg('type','neumann');
-            default_arg('parameter', []);
-
-            [e, d_n, d_t, coeff_n, coeff_t, s, gamm, halfnorm_inv  ,              ~,          ~, ~, scale_factor] = obj.get_boundary_ops(boundary);
-            switch type
-                % Dirichlet boundary condition
-                case {'D','d','dirichlet'}
-                    % v denotes the solution in the neighbour domain
-                    tuning = 1.2;
-                    % tuning = 20.2;
-                    [e, d_n, d_t, coeff_n, coeff_t, s, gamm, halfnorm_inv_n, halfnorm_inv_t, halfnorm_t] = obj.get_boundary_ops(boundary);
-
-                    a_n = spdiag(coeff_n);
-                    a_t = spdiag(coeff_t);
-
-                    F = (s * a_n * d_n' + s * a_t*d_t')';
-
-                    u = obj;
-
-                    b1 = gamm*u.lambda./u.a11.^2;
-                    b2 = gamm*u.lambda./u.a22.^2;
-
-                    tau  = -1./b1 - 1./b2;
-                    tau = tuning * spdiag(tau);
-                    sig1 = 1;
-
-                    penalty_parameter_1 = halfnorm_inv_n*(tau + sig1*halfnorm_inv_t*F*e'*halfnorm_t)*e;
-
-                    closure = obj.Ji*obj.c^2 * penalty_parameter_1*e';
-                    penalty = -obj.Ji*obj.c^2 * penalty_parameter_1;
-
-
-                % Neumann boundary condition
-                case {'N','n','neumann'}
-                    c = obj.c;
-
-                    a_n = spdiags(coeff_n,0,length(coeff_n),length(coeff_n));
-                    a_t = spdiags(coeff_t,0,length(coeff_t),length(coeff_t));
-                    d = (a_n * d_n' + a_t*d_t')';
-
-                    tau1 = -s;
-                    tau2 = 0;
-                    tau = c.^2 * obj.Ji*(tau1*e + tau2*d);
-
-                    closure = halfnorm_inv*tau*d';
-                    penalty = -halfnorm_inv*tau;
-
-                % Characteristic boundary condition
-                case {'characteristic', 'char', 'c'}
-                    default_arg('parameter', 1);
-                    beta = parameter;
-                    c = obj.c;
-
-                    a_n = spdiags(coeff_n,0,length(coeff_n),length(coeff_n));
-                    a_t = spdiags(coeff_t,0,length(coeff_t),length(coeff_t));
-                    d = s*(a_n * d_n' + a_t*d_t')'; % outward facing normal derivative
-
-                    tau = -c.^2 * 1/beta*obj.Ji*e;
-
-                    warning('is this right?! /c?')
-                    closure{1} = halfnorm_inv*tau/c*spdiag(scale_factor)*e';
-                    closure{2} = halfnorm_inv*tau*beta*d';
-                    penalty = -halfnorm_inv*tau;
-
-                % Unknown, boundary condition
-                otherwise
-                    error('No such boundary condition: type = %s',type);
-            end
-        end
-
-        function [closure, penalty] = interface(obj,boundary,neighbour_scheme,neighbour_boundary)
-            % u denotes the solution in the own domain
-            % v denotes the solution in the neighbour domain
-            tuning = 1.2;
-            % tuning = 20.2;
-            [e_u, d_n_u, d_t_u, coeff_n_u, coeff_t_u, s_u, gamm_u, halfnorm_inv_u_n, halfnorm_inv_u_t, halfnorm_u_t, I_u] = obj.get_boundary_ops(boundary);
-            [e_v, d_n_v, d_t_v, coeff_n_v, coeff_t_v, s_v, gamm_v, halfnorm_inv_v_n, halfnorm_inv_v_t, halfnorm_v_t, I_v] = neighbour_scheme.get_boundary_ops(neighbour_boundary);
-
-            a_n_u = spdiag(coeff_n_u);
-            a_t_u = spdiag(coeff_t_u);
-            a_n_v = spdiag(coeff_n_v);
-            a_t_v = spdiag(coeff_t_v);
-
-            F_u = (s_u * a_n_u * d_n_u' + s_u * a_t_u*d_t_u')';
-            F_v = (s_v * a_n_v * d_n_v' + s_v * a_t_v*d_t_v')';
-
-            u = obj;
-            v = neighbour_scheme;
-
-            b1_u = gamm_u*u.lambda(I_u)./u.a11(I_u).^2;
-            b2_u = gamm_u*u.lambda(I_u)./u.a22(I_u).^2;
-            b1_v = gamm_v*v.lambda(I_v)./v.a11(I_v).^2;
-            b2_v = gamm_v*v.lambda(I_v)./v.a22(I_v).^2;
-
-            tau = -1./(4*b1_u) -1./(4*b1_v) -1./(4*b2_u) -1./(4*b2_v);
-            tau = tuning * spdiag(tau);
-            sig1 = 1/2;
-            sig2 = -1/2;
-
-            penalty_parameter_1 = halfnorm_inv_u_n*(e_u*tau + sig1*halfnorm_inv_u_t*F_u*e_u'*halfnorm_u_t*e_u);
-            penalty_parameter_2 = halfnorm_inv_u_n * sig2 * e_u;
-
-
-            closure = obj.Ji*obj.c^2 * ( penalty_parameter_1*e_u' + penalty_parameter_2*F_u');
-            penalty = obj.Ji*obj.c^2 * (-penalty_parameter_1*e_v' + penalty_parameter_2*F_v');
-        end
-
-        % Ruturns the boundary ops and sign for the boundary specified by the string boundary.
-        % The right boundary is considered the positive boundary
-        %
-        %  I -- the indecies of the boundary points in the grid matrix
-        function [e, d_n, d_t, coeff_n, coeff_t, s, gamm, halfnorm_inv_n, halfnorm_inv_t, halfnorm_t, I, scale_factor] = get_boundary_ops(obj, boundary)
-
-            % gridMatrix = zeros(obj.m(2),obj.m(1));
-            % gridMatrix(:) = 1:numel(gridMatrix);
-
-            ind = grid.funcToMatrix(obj.grid, 1:prod(obj.m));
-
-            switch boundary
-                case 'w'
-                    e = obj.e_w;
-                    d_n = obj.du_w;
-                    d_t = obj.dv_w;
-                    s = -1;
-
-                    I = ind(1,:);
-                    coeff_n = obj.a11(I);
-                    coeff_t = obj.a12(I);
-                    scale_factor = sqrt(obj.x_v(I).^2 + obj.y_v(I).^2);
-                case 'e'
-                    e = obj.e_e;
-                    d_n = obj.du_e;
-                    d_t = obj.dv_e;
-                    s = 1;
-
-                    I = ind(end,:);
-                    coeff_n = obj.a11(I);
-                    coeff_t = obj.a12(I);
-                    scale_factor = sqrt(obj.x_v(I).^2 + obj.y_v(I).^2);
-                case 's'
-                    e = obj.e_s;
-                    d_n = obj.dv_s;
-                    d_t = obj.du_s;
-                    s = -1;
-
-                    I = ind(:,1)';
-                    coeff_n = obj.a22(I);
-                    coeff_t = obj.a12(I);
-                    scale_factor = sqrt(obj.x_u(I).^2 + obj.y_u(I).^2);
-                case 'n'
-                    e = obj.e_n;
-                    d_n = obj.dv_n;
-                    d_t = obj.du_n;
-                    s = 1;
-
-                    I = ind(:,end)';
-                    coeff_n = obj.a22(I);
-                    coeff_t = obj.a12(I);
-                    scale_factor = sqrt(obj.x_u(I).^2 + obj.y_u(I).^2);
-                otherwise
-                    error('No such boundary: boundary = %s',boundary);
-            end
-
-            switch boundary
-                case {'w','e'}
-                    halfnorm_inv_n = obj.Hiu;
-                    halfnorm_inv_t = obj.Hiv;
-                    halfnorm_t = obj.Hv;
-                    gamm = obj.gamm_u;
-                case {'s','n'}
-                    halfnorm_inv_n = obj.Hiv;
-                    halfnorm_inv_t = obj.Hiu;
-                    halfnorm_t = obj.Hu;
-                    gamm = obj.gamm_v;
-            end
-        end
-
-        function N = size(obj)
-            N = prod(obj.m);
-        end
-
-
-    end
-end
\ No newline at end of file
--- a/+scheme/bcSetup.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+scheme/bcSetup.m	Tue Feb 12 17:12:42 2019 +0100
@@ -1,10 +1,9 @@
-% function [closure, S] = bcSetup(diffOp, bc)
 % Takes a diffOp and a cell array of boundary condition definitions.
 % Each bc is a struct with the fields
 %  * type     -- Type of boundary condition
 %  * boundary -- Boundary identifier
 %  * data     -- A function_handle for a function which provides boundary data.(see below)
-% Also takes S_sign which modifies the sign of S, [-1,1]
+% Also takes S_sign which modifies the sign of the penalty function, [-1,1]
 % Returns a closure matrix and a forcing function S.
 %
 % The boundary data function can either be a function of time or a function of time and space coordinates.
@@ -16,97 +15,6 @@
     assertType(bcs, 'cell');
     assert(S_sign == 1 || S_sign == -1, 'S_sign must be either 1 or -1');
 
-    verifyBcFormat(bcs, diffOp);
-
-    % Setup storage arrays
-    closure = spzeros(size(diffOp));
-    gridData = {};
-    symbolicData = {};
-
-    % Collect closures, penalties and data
-    for i = 1:length(bcs)
-        [localClosure, penalty] = diffOp.boundary_condition(bcs{i}.boundary, bcs{i}.type);
-        closure = closure + localClosure;
-
-        [ok, isSymbolic, data] = parseData(bcs{i}, penalty, diffOp.grid);
-
-        if ~ok
-            % There was no data
-            continue
-        end
-
-        if isSymbolic
-            symbolicData{end+1} = data;
-        else
-            gridData{end+1} = data;
-        end
-    end
-
-    % Setup penalty function
-    O = spzeros(size(diffOp),1);
-    function v = S_fun(t)
-        v = O;
-        for i = 1:length(gridData)
-            v = v + gridData{i}.penalty*gridData{i}.func(t);
-        end
-
-        for i = 1:length(symbolicData)
-            v = v + symbolicData{i}.penalty*symbolicData{i}.func(t, symbolicData{i}.coords{:});
-        end
-
-        v = S_sign * v;
-    end
-    S = @S_fun;
+    [closure, penalties] = scheme.bc.closureSetup(diffOp, bcs);
+    S = scheme.bc.forcingSetup(diffOp, penalties, bcs, S_sign);
 end
-
-function verifyBcFormat(bcs, diffOp)
-    for i = 1:length(bcs)
-        assertType(bcs{i}, 'struct');
-        assertStructFields(bcs{i}, {'type', 'boundary'});
-
-        if ~isfield(bcs{i}, 'data') || isempty(bcs{i}.data)
-            continue
-        end
-
-        if ~isa(bcs{i}.data, 'function_handle')
-            error('bcs{%d}.data should be a function of time or a function of time and space',i);
-        end
-
-        b = diffOp.grid.getBoundary(bcs{i}.boundary);
-
-        dim = size(b,2);
-
-        if nargin(bcs{i}.data) == 1
-            % Grid data (only function of time)
-            assertSize(bcs{i}.data(0), 1, size(b));
-        elseif nargin(bcs{i}.data) ~= 1+dim
-           error('sbplib:scheme:bcSetup:DataWrongNumberOfArguments', 'bcs{%d}.data has the wrong number of input arguments. Must be either only time or time and space.', i);
-        end
-    end
-end
-
-function [ok, isSymbolic, dataStruct] = parseData(bc, penalty, grid)
-    if ~isfield(bc,'data') || isempty(bc.data)
-        isSymbolic = [];
-        dataStruct = struct();
-        ok = false;
-        return
-    end
-    ok = true;
-
-    nArg = nargin(bc.data);
-
-    if nArg > 1
-        % Symbolic data
-        isSymbolic = true;
-        coord = grid.getBoundary(bc.boundary);
-        dataStruct.penalty = penalty;
-        dataStruct.func = bc.data;
-        dataStruct.coords = num2cell(coord, 1);
-    else
-        % Grid data
-        isSymbolic = false;
-        dataStruct.penalty = penalty;
-        dataStruct.func = bcs{i}.data;
-    end
-end
--- a/+scheme/error1d.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,4 +0,0 @@
-function e = error1d(discr, v1, v2)
-    h = discr.h;
-    e = sqrt(h*sum((v1-v2).^2));
-end
\ No newline at end of file
--- a/+scheme/error2d.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,5 +0,0 @@
-function e = error2d(discr, v1, v2)
-    % If v1 and v2 are more complex types, something like grid functions... Then we may use .getVectorFrom here!
-    h = discr.h;
-    e = sqrt(h.^2*sum((v1-v2).^2));
-end
\ No newline at end of file
--- a/+scheme/errorMax.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,3 +0,0 @@
-function e = errorMax(~, v1, v2)
-    e = max(abs(v1-v2));
-end
--- a/+scheme/errorRelative.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,3 +0,0 @@
-function e = errorRelative(~,v1,v2)
-    e = sqrt(sum((v1-v2).^2)/sum(v2.^2));
-end
\ No newline at end of file
--- a/+scheme/errorSbp.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,6 +0,0 @@
-function e = errorSbp(discr, v1, v2)
-    % If v1 and v2 are more complex types, something like grid functions... Then we may use .getVectorFrom here!
-    H = discr.H;
-    err = v2 - v1;
-    e = sqrt(err'*H*err);
-end
\ No newline at end of file
--- a/+scheme/errorVector.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,3 +0,0 @@
-function e = errorVector(~, v1, v2)
-    e = v2-v1;
-end
\ No newline at end of file
--- a/+time/+cdiff/cdiff.m	Thu Sep 20 12:05:20 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,16 +0,0 @@
-% Takes a step of
-%   v_tt = Dv+Ev_t+S
-%
-%   1/k^2 * (v_next - 2v + v_prev) = Dv  + E 1/(2k)(v_next - v_prev) + S
-%
-function [v_next, v] = cdiff(v, v_prev, k, D, E, S)
-    %   1/k^2 * (v_next - 2v + v_prev) = Dv  + E 1/(2k)(v_next - v_prev) + S
-    %       ekv to
-    %   A v_next = B v + C v_prev + S
-    I = speye(size(D));
-    A =  1/k^2 * I - 1/(2*k)*E;
-    B =  2/k^2 * I + D;
-    C = -1/k^2 * I - 1/(2*k)*E;
-
-    v_next = A\(B*v + C*v_prev + S);
-end
\ No newline at end of file
--- a/+time/Cdiff.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+time/Cdiff.m	Tue Feb 12 17:12:42 2019 +0100
@@ -1,36 +1,45 @@
 classdef Cdiff < time.Timestepper
     properties
-        D
-        E
-        S
+        A, B, C
+        AA, BB, CC
+        G
         k
         t
-        v
-        v_prev
+        v, v_prev
         n
     end
 
 
     methods
-        % Solves u_tt = Du + Eu_t + S
-        % D, E, S can either all be constants or all be function handles,
-        % They can also be omitted by setting them equal to the empty matrix.
-        % Cdiff(D, E, S, k, t0, n0, v, v_prev)
-        function obj = Cdiff(D, E, S, k, t0, n0, v, v_prev)
-            m = length(v);
-            default_arg('E',sparse(m,m));
-            default_arg('S',sparse(m,1));
+        % Solves
+        %   A*v_tt + B*v_t + C*v = G(t)
+        %   v(t0) = v0
+        %   v_t(t0) = v0t
+        % starting at time t0 with timestep k
+        % Using
+        % A*Dp*Dm*v_n + B*D0*v_n + C*v_n = G(t_n)
+        function obj = Cdiff(A, B, C, G, v0, v0t, k, t0)
+            m = length(v0);
+            default_arg('A', speye(m));
+            default_arg('B', sparse(m,m));
+            default_arg('G', @(t) sparse(m,1));
+            default_arg('t0', 0);
 
-            obj.D = D;
-            obj.E = E;
-            obj.S = S;
+            obj.A = A;
+            obj.B = B;
+            obj.C = C;
+            obj.G = G;
 
+            % Rewrite as AA*v_(n+1) + BB*v_n + CC*v_(n-1) = G(t_n)
+            obj.AA =    A/k^2 + B/(2*k);
+            obj.BB = -2*A/k^2 + C;
+            obj.CC =    A/k^2 - B/(2*k);
 
             obj.k = k;
-            obj.t = t0;
-            obj.n = n0;
-            obj.v = v;
-            obj.v_prev = v_prev;
+            obj.v_prev = v0;
+            obj.v = v0 + k*v0t;
+            obj.t = t0+k;
+            obj.n = 1;
         end
 
         function [v,t] = getV(obj)
@@ -43,10 +52,21 @@
             t = obj.t;
         end
 
+        function E = getEnergy(obj)
+            v  = obj.v;
+            vp = obj.v_prev;
+            vt = (obj.v - obj.v_prev)/obj.k;
+
+            E = vt'*obj.A*vt + v'*obj.C*vp;
+        end
+
         function obj = step(obj)
-            [obj.v, obj.v_prev] = time.cdiff.cdiff(obj.v, obj.v_prev, obj.k, obj.D, obj.E, obj.S);
+            v_next = obj.AA\(-obj.BB*obj.v - obj.CC*obj.v_prev + obj.G(obj.t));
+
+            obj.v_prev = obj.v;
+            obj.v      = v_next;
             obj.t = obj.t + obj.k;
             obj.n = obj.n + 1;
         end
     end
-end
\ No newline at end of file
+end
--- a/+time/CdiffImplicit.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+time/CdiffImplicit.m	Tue Feb 12 17:12:42 2019 +0100
@@ -1,7 +1,8 @@
 classdef CdiffImplicit < time.Timestepper
     properties
-        A, B, C, G
+        A, B, C
         AA, BB, CC
+        G
         k
         t
         v, v_prev
@@ -13,59 +14,36 @@
 
     methods
         % Solves
-        %   A*u_tt + B*u + C*v_t = G(t)
-        %   u(t0) = f1
-        %   u_t(t0) = f2
-        % starting at time t0 with timestep k
-        function obj = CdiffImplicit(A, B, C, G, f1, f2, k, t0)
-            default_arg('A', []);
-            default_arg('C', []);
-            default_arg('G', []);
-            default_arg('f1', 0);
-            default_arg('f2', 0);
+        %   A*v_tt + B*v_t + C*v = G(t)
+        %   v(t0) = v0
+        %   v_t(t0) = v0t
+        % starting at time t0 with timestep
+        % Using
+        % A*Dp*Dm*v_n + B*D0*v_n + C*I0*v_n = G(t_n)
+        function obj = CdiffImplicit(A, B, C, G, v0, v0t, k, t0)
+            m = length(v0);
+            default_arg('A', speye(m));
+            default_arg('B', sparse(m,m));
+            default_arg('G', @(t) sparse(m,1));
             default_arg('t0', 0);
 
-            m = size(B,1);
-
-            if isempty(A)
-                A = speye(m);
-            end
-
-            if isempty(C)
-                C = sparse(m,m);
-            end
-
-            if isempty(G)
-                G = @(t) sparse(m,1);
-            end
-
-            if isempty(f1)
-                f1 = sparse(m,1);
-            end
-
-            if isempty(f2)
-                f2 = sparse(m,1);
-            end
-
             obj.A = A;
             obj.B = B;
             obj.C = C;
             obj.G = G;
 
-            AA = 1/k^2*A + 1/2*B + 1/(2*k)*C;
-            BB = -2/k^2*A;
-            CC = 1/k^2*A + 1/2*B - 1/(2*k)*C;
-            % AA*v_next + BB*v + CC*v_prev == G(t_n)
+            % Rewrite as AA*v_(n+1) + BB*v_n + CC*v_(n-1) = G(t_n)
+            AA =    A/k^2 + B/(2*k) + C/2;
+            BB = -2*A/k^2;
+            CC =    A/k^2 - B/(2*k) + C/2;
 
             obj.AA = AA;
             obj.BB = BB;
             obj.CC = CC;
 
-            v_prev = f1;
+            v_prev = v0;
             I = speye(m);
-            % v = (1/k^2*A)\((1/k^2*A - 1/2*B)*f1 + (1/k*I - 1/2*C)*f2 + 1/2*G(0));
-            v = f1 + k*f2;
-
+            v = v0 + k*v0t;
 
             if ~issparse(A) || ~issparse(B) || ~issparse(C)
                 error('LU factorization with full pivoting only works for sparse matrices.')
@@ -78,7 +56,6 @@
             obj.p = p;
             obj.q = q;
 
-
             obj.k = k;
             obj.t = t0+k;
             obj.n = 1;
@@ -92,17 +69,17 @@
         end
 
         function [vt,t] = getVt(obj)
-            % Calculate next time step to be able to do centered diff.
-            v_next = zeros(size(obj.v));
-            b = obj.G(obj.t) - obj.BB*obj.v - obj.CC*obj.v_prev;
+            vt = (obj.v-obj.v_prev)/obj.k; % Could be improved using u_tt = f(u))
+            t = obj.t;
+        end
 
-            y = obj.L\b(obj.p);
-            z = obj.U\y;
-            v_next(obj.q) = z;
+        % Calculate the conserved energy (Dm*v_n)^2_A + Im*v_n^2_B
+        function E = getEnergy(obj)
+            v  = obj.v;
+            vp = obj.v_prev;
+            vt = (obj.v - obj.v_prev)/obj.k;
 
-
-            vt = (v_next-obj.v_prev)/(2*obj.k);
-            t = obj.t;
+            E = vt'*obj.A*vt + 1/2*(v'*obj.C*v + vp'*obj.C*vp);
         end
 
         function obj = step(obj)
@@ -123,30 +100,3 @@
         end
     end
 end
-
-
-
-
-
-%%% Derivation
-% syms A B C G
-% syms n k
-% syms f1 f2
-
-% v = symfun(sym('v(n)'),n);
-
-
-% d = A/k^2 * (v(n+1) - 2*v(n) +v(n-1)) + B/2*(v(n+1)+v(n-1)) + C/(2*k)*(v(n+1) - v(n-1)) == G
-% ic1 = v(0) == f1
-% ic2 = A/k*(v(1)-f1) + k/2*(B*f1 + C*f2 - G) - f2 == 0
-
-% c = collect(d, [v(n) v(n-1) v(n+1)]) % (-(2*A)/k^2)*v(n) + (B/2 + A/k^2 - C/(2*k))*v(n - 1) + (B/2 + A/k^2 + C/(2*k))*v(n + 1) == G
-% syms AA BB CC
-% % AA = B/2 + A/k^2 + C/(2*k)
-% % BB = -(2*A)/k^2
-% % CC = B/2 + A/k^2 - C/(2*k)
-% s = subs(c, [B/2 + A/k^2 + C/(2*k), -(2*A)/k^2, B/2 + A/k^2 - C/(2*k)], [AA, BB, CC])
-
-
-% ic2_a = collect(ic2, [v(1) f1 f2]) % (A/k)*v(1) + ((B*k)/2 - A/k)*f1 + ((C*k)/2 - 1)*f2 - (G*k)/2 == 0
-
--- a/+util/ReplaceableString.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/+util/ReplaceableString.m	Tue Feb 12 17:12:42 2019 +0100
@@ -58,3 +58,5 @@
 function b = padStr(a, n)
     b = sprintf('%-*s', n, a);
 end
+
+% TODO: Add a debug mode which prints without replacing?
--- a/Map.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/Map.m	Tue Feb 12 17:12:42 2019 +0100
@@ -59,6 +59,9 @@
         function v = subsref(obj, S)
             switch S(1).type
                 case '()'
+                    if length(S.subs) > 1
+                        error('sbplib:Map:multipleKeys', 'Multiple dimensions are not supported. Use a cell array as a key instead.');
+                    end
                     k = S.subs{1};
                     try
                         v = get(obj, k);
@@ -81,6 +84,9 @@
         function obj = subsasgn(obj, S, v);
             switch S(1).type
                 case '()'
+                    if length(S.subs) > 1
+                        error('sbplib:Map:multipleKeys', 'Multiple dimensions are not supported. Use a cell array as a key instead.');
+                    end
                     k = S.subs{1};
                     set(obj, k, v);
                 otherwise
--- a/MapTest.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/MapTest.m	Tue Feb 12 17:12:42 2019 +0100
@@ -12,6 +12,21 @@
     };
 end
 
+function testMultiKey(testCase)
+    map = Map
+
+    function setMultiKey()
+        map(1,2) = 1;
+    end
+
+    function getMultiKey()
+        v = map(1,2);
+    end
+
+    testCase.verifyError(@setMultiKey,'sbplib:Map:multipleKeys')
+    testCase.verifyError(@getMultiKey,'sbplib:Map:multipleKeys')
+end
+
 function testSetAndGet(testCase)
     keyValuePairs = getKeyValuePairs();
 
--- a/TextTable.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/TextTable.m	Tue Feb 12 17:12:42 2019 +0100
@@ -41,6 +41,14 @@
             obj.fmtArray{i,j} = fmt;
         end
 
+        function formatGrid(obj, I, J, fmt)
+            for i = I
+                for j = J
+                    obj.fmtArray{i,j} = fmt;
+                end
+            end
+        end
+
         function formatRow(obj, i, fmt)
             obj.fmtArray(i,:) = {fmt};
         end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/arrowAnnotation.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,23 @@
+% Draw an arrow from p1 to p2, with text attached
+function [h] = arrowAnnotation(p1,p2)
+    ah = gca;
+    xl = ah.XLim(1);
+    xr = ah.XLim(2);
+
+    yl = ah.YLim(1);
+    yr = ah.YLim(2);
+
+    dx = xr - xl;
+    dy = yr - yl;
+
+    s = [
+        ah.Position(1) + (p1(1) - xl)/dx*ah.Position(3),
+        ah.Position(1) + (p2(1) - xl)/dx*ah.Position(3),
+    ];
+    t = [
+        ah.Position(2) + (p1(2) - yl)/dy*ah.Position(4),
+        ah.Position(2) + (p2(2) - yl)/dy*ah.Position(4),
+    ];
+
+    h = annotation('arrow', s, t);
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/assertLength.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,4 @@
+function assertLength(A,l)
+    assert(isvector(A), sprintf('Expected ''%s'' to be a vector, got matrix of size %s',inputname(1), toString(size(A))));
+    assert(length(A) == l, sprintf('Expected ''%s'' to have length %d, got %d', inputname(1), l, length(A)));
+end
--- a/assertSize.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/assertSize.m	Tue Feb 12 17:12:42 2019 +0100
@@ -2,13 +2,13 @@
 function assertSize(A,varargin)
     if length(varargin) == 1
         s = varargin{1};
-        errmsg = sprintf('Expected %s to have size %s, got: %s',inputname(1), toString(s), toString(size(A)));
-        assert(all(size(A) == s), errmsg);
+        assert(length(size(A)) == length(s), sprintf('Expected ''%s'' to have dimension %d, got %d', inputname(1), length(s), length(size(A))));
+        assert(all(size(A) == s), sprintf('Expected ''%s'' to have size %s, got: %s',inputname(1), toString(s), toString(size(A))));
     elseif length(varargin) == 2
         dim = varargin{1};
         s = varargin{2};
 
-        errmsg = sprintf('Expected %s to have size %d along dimension %d, got: %d',inputname(1), s, dim, size(A,dim));
+        errmsg = sprintf('Expected ''%s'' to have size %d along dimension %d, got: %d',inputname(1), s, dim, size(A,dim));
         assert(size(A,dim) == s, errmsg);
     else
         error('Expected 2 or 3 arguments to assertSize()');
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dealStruct.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,18 @@
+function varargout = dealStruct(s, fields)
+    default_arg('fields', []);
+
+    if isempty(fields)
+        out = dealFields(s, fieldnames(s));
+        varargout = out(1:nargout);
+    else
+        assert(nargout == length(fields), 'Number of output arguements must match the number of fieldnames provided');
+        varargout = dealFields(s, fields);
+    end
+end
+
+function out = dealFields(s, fields)
+    out = cell(1, length(fields));
+    for i = 1:length(fields)
+        out{i} = s.(fields{i});
+    end
+end
--- a/default_field.m	Thu Sep 20 12:05:20 2018 +0200
+++ b/default_field.m	Tue Feb 12 17:12:42 2019 +0100
@@ -1,7 +1,7 @@
 function default_field(s, f, val)
-    if isfield(s,f)
+    if isfield(s,f) && ~isempty(s.(f))
         return
     end
     s.(f) = val;
     assignin('caller', inputname(1),s);
-end
\ No newline at end of file
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hgRevision.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,8 @@
+% Returns the short mercurial revision Id.
+%  ok is false if there are uncommited changes.
+function [revId, ok] = hgRevision()
+    [~, s] = system('hg id -i');
+    revId = strtrim(s);
+
+    ok = s(end) ~= '+';
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/stuffStruct.m	Tue Feb 12 17:12:42 2019 +0100
@@ -0,0 +1,8 @@
+function s = stuffStruct(varargin)
+    s = struct();
+
+    for i = 1:nargin
+        assert(~isempty(inputname(i)), 'All inputs must be variables.');
+        s.(inputname(i)) = varargin{i};
+    end
+end