[Octave-bug-tracker] [bug #40324] Concatenating Sparse matrices throws OOM

[David Bateman]

Follow-up Comment #4, bug #40324 (project octave):

How exactly do you "patch" numel ? This method is doing what it supposed to do
for sparse matrices, but given the limitation of 32 bit integers it will never
return the right value for large sparse matrices. The only "patch" I can
imagine that has a chance of fixing this is to always use 64 bit integers for
numel for all types, and even that won't fix


s = speye (2^32);
q = [s, s];
 

when Octave is built with 64 bit integers. Though you might argue that it'll
be a while till we'll see matrices this large. In this case, the special case
is justified as sparse matrices don't even use the 1x1 optimisation in
pt-mat.cc

So for your question, yes I think its worth avoiding numel wherever possible
when dealing with sparse matrices

David


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