U = [ 
 1,  1,  0, -1, -1,  0;
 0,  1,  1,  1,  0, -1;
-1, -1, -1, -1, -1, -1 ];

%U = [
%    1, 2;
%    2, 4;
%    -1, -2 ];

Usimplified = PCC_simplify(U);
U
Usimplified
