Singular

LIB "tateProdCplxNegGrad.lib";
// example 1
intvec c1 = 1,2;
def (S1,E1) = productOfProjectiveSpaces(c1);
setring(S1);
module M1 = x(0)(0),x(1)(0)^3 + x(1)(1)^3 +x(1)(2)^3;
intmat grading1[2][1] = 0,0;
M1 = setModuleGrading(M1,grading1);
sufficientlyPositiveMultidegree(M1);
==> 1,3
// example 2
intvec c2 = 1,1;
def (S2,E2) = productOfProjectiveSpaces(c2);
setring(S2);
intmat grading2[2][1] = -1,-1;
module M2 = 0;
M2 = setModuleGrading(M2,grading2);
sufficientlyPositiveMultidegree(M2);
==> -1,-1
// example 3
intvec c3 = 1,1,1;
def (S3,E3) = productOfProjectiveSpaces(c3);
setring(S3);
module M3 = 0;
intmat grading3[3][1] = -1,-1,-1;
M3 = setModuleGrading(M3,grading3);
sufficientlyPositiveMultidegree(M3);
==> -1,-1,-1