--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/D1UpwindCompatible.m	Sun May 31 20:16:54 2020 -0700
@@ -0,0 +1,64 @@
+classdef D1UpwindCompatible < sbp.OpSet
+    properties
+        Dp, Dm % SBP operator approximating first derivative
+        H % Norm matrix
+        HI % H^-1
+        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 = D1UpwindCompatible(m,lim,order)
+
+            x_l = lim{1};
+            x_r = lim{2};
+            L = x_r-x_l;
+            obj.h = L/(m-1);
+            obj.x = linspace(x_l,x_r,m)';
+
+            ops = sbp.D2Standard(m, lim, order);
+            D1 = ops.D1;
+            H = ops.H;
+
+            obj.H = H;
+            obj.HI = inv(H);
+            obj.e_l = ops.e_l;
+            obj.e_r = ops.e_r;
+
+            switch order
+                case 2
+                    ops = sbp.D2Standard(m, lim, 2);
+                    Dp = D1 + obj.h^1*1/2*(H\ops.M);
+                    Dm = D1 - obj.h^1*1/2*(H\ops.M);
+                case 4
+                    ops = sbp.D4Variable(m, lim, 2);
+                    Dp = D1 - obj.h^3*1/12*(H\ops.M4);
+                    Dm = D1 + obj.h^3*1/12*(H\ops.M4);
+                otherwise
+                    error('Invalid operator order %d.',order);
+            end
+
+            obj.Dp = Dp;
+            obj.Dm = Dm;
+
+            obj.m = m;
+        	obj.borrowing = [];
+
+        end
+
+        function str = string(obj)
+            str = [class(obj) '_' num2str(obj.order)];
+        end
+    end
+
+
+end
+
+
+
+
+