Declaration of EntriesOfHomalgMatrix(AsListList)

[kamalsaleh]

These methods are currently declared as operations applied on the homalg matrix. I have been wondering why to not declare them as attributes to the matrix?

Setting them as attributes would speed up the running time of multiples calls in many instances. For example in case of external rings in singular or magma.

[mohamed-barakat]

An external homalg matrix has its defining data in the external CAS. The idea is to store small attributes in GAP and the above attributes are huge. We can think about introducing a marking for matrices which enables them to store this data. What do you think?

[kamalsaleh]

mmm, very sensible. I was thinking about introducing two attributes:

##
DeclareAttribute( "EntriesOfHomalgMatrixAttr", IsHomalgMatrix );
DeclareAttribute( "EntriesOfHomalgMatrixAsListListAttr", IsHomalgMatrix );

##
InstallMethod( EntriesOfHomalgMatrixAttr, [ IsHomalgMatrix ], EntriesOfHomalgMatrix );
InstallMethod( EntriesOfHomalgMatrixAsListListAttr, [ IsHomalgMatrix ], EntriesOfHomalgMatrixAsListList );

These give enough flexibility and the user can use them (at the cost of memory) or not.

[kamalsaleh]

or maybe store the output inside the record of the matrix, which can be triggered by an optional argument.