Home Online Manual
Top
Back: isPositive
Forward: areZeroElements
FastBack:
FastForward:
Up: multigrading_lib
Top: Singular Manual
Contents: Table of Contents
Index: Index
About: About this document

D.15.25.35 isZeroElement

Procedure from library multigrading.lib (see multigrading_lib).

Usage:
isZeroElement(d, [T]); intvec d, group T

Purpose:
For a integer vector 'd' representing the multidegree of some polynomial or vector this method computes if the multidegree is contained in the grading group group (either set globally or given as an optional argument), i.e. if it is zero in the multigrading.

Example:
 
LIB "multigrading.lib";
ring r = 0,(x,y,z),dp;
intmat g[2][3]=
1,0,1,
0,1,1;
intmat t[2][1]=
-2,
1;
intmat tt[2][1]=
1,
-1;
setBaseMultigrading(g,t);
poly a = x10yz;
poly b = x8y2z;
poly c = x4z2;
poly d = y5;
poly e = x2y2;
poly f = z2;
intvec v1 = multiDeg(a) - multiDeg(b);
v1;
==> 2,-1
isZeroElement(v1);
==> 1
isZeroElement(v1, tt);
==> 0
intvec v2 = multiDeg(a) - multiDeg(c);
v2;
==> 5,0
isZeroElement(v2);
==> 0
isZeroElement(v2, tt);
==> 0
intvec v3 = multiDeg(e) - multiDeg(f);
v3;
==> 0,0
isZeroElement(v3);
==> 1
isZeroElement(v3, tt);
==> 1
intvec v4 = multiDeg(c) - multiDeg(d);
v4;
==> 6,-3
isZeroElement(v4);
==> 1
isZeroElement(v4, tt);
==> 0