--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/D1Nonequidistant.m	Mon Sep 12 12:53:02 2016 +0200
@@ -0,0 +1,94 @@
+classdef D1Nonequidistant < sbp.OpSet
+    properties
+        D1 % SBP operator approximating first derivative
+        H % Norm matrix
+        HI % H^-1
+        Q % Skew-symmetric matrix
+        e_l % Left boundary operator
+        e_r % Right boundary operator
+        m % Number of grid points.
+        h % Step size
+        x % grid
+        borrowing % Struct with borrowing limits for different norm matrices
+    end
+    
+    methods
+        function obj = D1Nonequidistant(m,lim,order,option)
+            
+            default_arg('option','Accurate');
+            % 'Accurate' operators are optimized for accuracy
+            % 'Minimal' operators have the smallest possible boundary
+            %  closure
+            
+            x_l = lim{1};
+            x_r = lim{2};
+            L = x_r-x_l;
+            
+            switch option
+                
+                case {'Accurate','accurate','A'}
+                    
+                    if order == 4
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_4(m,L);
+                    elseif order == 6
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_6(m,L);
+                    elseif order == 8
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_8(m,L);
+                    elseif order == 10
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_10(m,L);
+                    elseif order == 12
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_12(m,L);
+                    else
+                        error('Invalid operator order %d.',order);
+                    end
+                    
+                case {'Minimal','minimal','M'}
+                    
+                    if order == 4
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_minimal_4(m,L);
+                    elseif order == 6
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_minimal_6(m,L);
+                    elseif order == 8
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_minimal_8(m,L);
+                    elseif order == 10
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_minimal_10(m,L);
+                    elseif order == 12
+                        [obj.D1,obj.H,obj.x,obj.h] = ...
+                            sbp.implementations.d1_noneq_minimal_12(m,L);
+                    else
+                        error('Invalid operator order %d.',order);
+                    end
+                    
+            end
+            
+            obj.x = obj.x + x_l;
+            
+            obj.e_l = sparse(m,1);
+            obj.e_r = sparse(m,1);
+            obj.e_l(1) = 1;
+            obj.e_r(m) = 1;
+            
+            obj.HI = inv(obj.H);
+            obj.Q = obj.H*obj.D1 - obj.e_r*obj.e_r' + obj.e_l*obj.e_l';
+            
+            obj.borrowing = [];
+            
+        end
+    end
+    
+
+end
+
+
+
+
+