--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+sbp/+implementations/d2_2.m	Fri Sep 23 10:40:12 2016 +0200
@@ -0,0 +1,43 @@
+function [H, HI, D1, D2, e_1, e_m, M, Q, S_1, S_m] = d2_2(m,h)
+    
+    BP = 1;
+    if(m<2*BP)
+        error(['Operator requires at least ' num2str(2*BP) ' grid points']);
+    end
+
+    e_1=sparse(m,1);e_1(1)=1;
+    e_m=sparse(m,1);e_m(m)=1;
+
+    H=(speye(m,m));H(1,1)=0.5;H(m,m)=0.5;
+    H=h*H;
+    HI=inv(H);
+    
+    diags   = -1:1;
+    stencil = [-1/2 0 1/2];
+    D1 = stripeMatrix(stencil, diags, m);
+    
+    D1(1,1)=-1;D1(1,2)=1;D1(m,m-1)=-1;D1(m,m)=1;
+    D1(m,m-1)=-1;D1(m,m)=1;
+    D1=D1/h;
+
+    Q=H*D1 + 1/2*(e_1*e_1') - 1/2*(e_m*e_m');
+
+    diags   = -1:1;
+    stencil = [1 -2 1];
+    D2 = stripeMatrix(stencil, diags, m);
+    
+    D2(1,1)=1;D2(1,2)=-2;D2(1,3)=1;
+    D2(m,m-2)=1;D2(m,m-1)=-2;D2(m,m)=1;
+    D2=D2/h^2;
+
+    S_U=[-3/2, 2, -1/2]/h;
+    S_1=sparse(1,m);
+    S_1(1:3)=S_U;
+    S_m=sparse(1,m);
+    S_m(m-2:m)=fliplr(-S_U);
+
+
+    M=-H*D2-e_1*S_1+e_m*S_m;
+    S_1 = S_1';
+    S_m = S_m';
+end
\ No newline at end of file