D.15.13.34 isPositive

Usage:

isPositive()

Purpose:

Computes whether the multigrading of the ring is positive. For computation theorem 8.6 of the Miller/Sturmfels book is used.

Returns:

true if the multigrading is positive

LIB "multigrading.lib";
printlevel = 3;
ring r = 0,(x,y),dp;
intmat A[1][2]=-1,1;
setBaseMultigrading(A);
isPositive();
==> 0
intmat B[1][2]=1,1;
setBaseMultigrading(B);
isPositive(B);
==> 1