[GAP Forum] Re: Another memory problem

mim_ at op.pl mim_ at op.pl
Mon Mar 17 11:32:17 GMT 2008

Thank you for the answers I have received ! It helped. I can use GAP with more memory now.

I believe there is a way to create function for Derivations, which consumes less memory. In the matrix A:= NullMat( n^2, n^3, R ); most of the entries are zeros.

I have tested it for algebra M6:=MatrixAlgebra(Rationals, 6);
There are 22476 non zero entries among 36^5=60466176.

I will try to create such function when I have more time.

Marek Mitros
mim_ at op.pl napisał(a): 
 > Example of error in Derivations:
 > A:=MatrixAlgebra(Rationals, 6);     ba:=Basis(A);     DA:=Derivations(ba);
 > Error is shown:
 > gap: cannot extend the workspace any more
 > gap: Press <Enter> to end program
 > I have following questions
 > 1. Why I can only start GAP with -m 300m option ?
 > 2. How to test how much memory given matrix A is using in GAP ?
 > 3. Has anybody tried to overwrite Derivations function to use smaller matrices ? E.g. we could declare smaller matrices NullMat( n^2, n^2, R ) in loop and solve partially equation via NullspaceMatDestructive(). Finally build intersection space for the result.
 > Regards,
 > Marek Mitros

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