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D.15.5.10 isTorsionElement
Procedure from library multigrading.lib (see multigrading_lib).
- Usage:
- isTorsionElement(intvec mdeg);
- Purpose:
- For a integer vector mdeg representing the multidegree of some polynomial
or vector this method computes if the multidegree is contained in the torsion
group, 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;
setBaseMultigrading(g,t);
poly a = x10yz;
poly b = x8y2z;
poly c = x4z2;
poly d = y5;
poly e = x2y2;
poly f = z2;
intvec v1 = mDeg(a) - mDeg(b);
v1;
==> 2,-1
isTorsionElement(v1);
==> 1
intvec v2 = mDeg(a) - mDeg(c);
v2;
==> 5,0
isTorsionElement(v2);
==> 0
intvec v3 = mDeg(e) - mDeg(f);
v3;
==> 0,0
isTorsionElement(v3);
==> 1
intvec v4 = mDeg(c) - mDeg(d);
v4;
==> 6,-3
isTorsionElement(v4);
==> 1
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