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D.15.23.34 isPositive

Procedure from library multigrading.lib (see multigrading_lib).

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

Example:
 
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