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7.5.23.0. showgrades
Procedure from library purityfiltration.lib (see purityfiltration_lib).

Usage:
showgrades(T), T list, which includes representation matrices of modules

Return:
list, gradenumbers of the entries in T

Purpose:
computes a list L with L[i]=gradenumber(M), M=D^p/D^qT[i]

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;
list T=purityFiltration(transpose(R))[2];
showgrades(T);
==> [1]:
==>    0
==> [2]:
==>    -1
==> [3]:
==>    2
==> [4]:
==>    3
// T[i] are i-1 pure (i=1,3,4) or zero (i=2)