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7.5.23.0. purelist
Procedure from library purityfiltration.lib (see purityfiltration_lib).
- Usage:
- purelist(T), T list, in which the i-th entry R=T[i] represents M=D^p/D^q(R^t)
- Return:
- list M, entries of M are 0 or 1
- Purpose:
- if T[i] is pure, M[i] is 1, else M[i] is 0
Example:
| | LIB "purityfiltration.lib";
ring D = 0,(x,y,z),dp;
matrix R[6][4]=
0,-2*x,z-2*y-x,-1,
0,z-2*x,2*y-3*x,1,
z,-6*x,-2*y-5*x,-1,
0,y-x,y-x,0,
y,-x,-y-x,0,
x,-x,-2*x,0;
is_pure(transpose(R));
==> 0
// R is not pure, so we do the purity filtration
list T=purityFiltration(transpose(R));
// all Elements of T[2] are either zero or pure
purelist(T[2]);
==> [1]:
==> 1
==> [2]:
==> 1
==> [3]:
==> 1
==> [4]:
==> 1
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