Singular

LIB "gradedModules.lib";
ring r=32003,(x,y,z),dp;
module A = grobj( module([x+y, x, 0, 0], [0, x+y, y, 0]), intvec(0,0,0,1) );
grview(A);
==> Graded homomorphism: r^3 + r(-1) <- r(-1)^2, given by a matrix, with degr\
   ees: 
==>      ..1 ..2 ....
==>      --- --- +...
==>   0 :  1   - |..1
==>   0 :  1   1 |..2
==>   0 :  -   1 |..3
==>   1 :  -   - |..4
==>      === ===     
==>        1   1     
module S = grshift( A,  6);
grview(S);
==> Graded homomorphism: r(6)^3 + r(5) <- r(5)^2, given by a matrix, with deg\
   rees: 
==>      ..1 ..2 ....
==>      --- --- +...
==>  -6 :  1   - |..1
==>  -6 :  1   1 |..2
==>  -6 :  -   1 |..3
==>  -5 :  -   - |..4
==>      === ===     
==>       -5  -5     
grview( grshift( grzero(), 100 ) ); // does nothing...
==> !! Warning: shifting '0 <- 0' leaves it as it unchanged!
==> Graded homomorphism: 0 <- 0, given by zero (0^2) matrix.