C31 = sparse(6,6);
C32 = sparse(6,6);
C31(1,2)=1;
C31(1,4)=1;
C31(1,5)=1;
C32(1,1)=1;
C32(1,2)=1;
C31(2,3)=1;
C31(2,5)=1;
C32(2,3)=1;
C31(5,4)=1;
C31(5,5)=1;
C32(5,6)=1;
C31(6,3)=1;
C31(6,6)=1;
C32(6,5)=1;