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MatFac15 :: Hom0

Hom0 -- compute the degree 0 part of a Hom group

Synopsis

Description

Computes the degree 0 part of the module Hom(M,N) without computing the whole module
i1 : kk=ZZ/10007;R=kk[y_0..y_2];
i3 : m=coker transpose random(R^{1,2},R^2);E=annihilator  m;

o4 : Ideal of R
i5 : RE=R/E; M=  m**RE; N=M;
i8 : time betti Hom0(M,M)
     -- used 0.0229353 seconds

            0 1
o8 = total: 4 1
        -1: . 1
         0: 4 .

o8 : BettiTally
i9 : time betti Hom(M,N)
     -- used 0.00223782 seconds

            0
o9 = total: 1
         0: 1

o9 : BettiTally

Ways to use Hom0 :