A = [1,1,0; 0,0,1; 1,1,1]';

B = [1,2; 1,1]';

C = [1,-1, 0, 0; 0, 1,-1, 0; 0, 0, 1,-1; -1, 0, 0, 1]';

D = [ 1,-1, 0; 0, 1,-1; 0,0,1]';
