[Octave-bug-tracker] [bug #47415] out of memory negating a permutation matrix

[Carlo de Falco]

Follow-up Comment #21, bug #47415 (project octave):

JWE I think exposing the details of the permutation matrix class
implementation to the end user would be really a bad thing.

The purpose of using a special class for permutation matrices is to exploit
the benefits in terms of speed and memory efficiency that are available in
this case.

For the case of a row/column permuted diagonal matrix, the next best possible
implementation in terms of speed and memory efficiency is that of a sparse
matrix.

Therefore converting a permutation matrix to sparse whenever an operation that
is not implemented is requested makes much more sense than falling back to
full matrices.

I agree with rik that low level details like handling overflows and '-0'
should be given lower priority.


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