[Octave-bug-tracker] [bug #56232] Octave crash when inverting an empty sparse matrix.

[Rik]

Update of bug #56232 (project octave):

                  Status:               Confirmed => Patch Submitted        

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Follow-up Comment #15:

Attached is a patch which does what I suggested, using nullptr for r and d, if
the sparse matrix is empty.  This actually doesn't have any performance impact
because the re-allocation code was being executed anyways.

This stops the crash, although the error is still


error: inv: sparse_lu: symbolic factorization failed


The second part of resolving this is to return a warning and some sort of
matrix as Matlab does.

For the full case, I get


octave:1> inv (zeros (2))
warning: matrix singular to machine precision
ans =

   Inf   Inf
   Inf   Inf



So that would be one possibility, to return a warning and the matrix


sparse (Inf (2))


Matlab returns


sparse ([Inf, NaN;
         NaN, Inf])


but that is probably just an artifact of the implementation and needn't be
copied exactly unless we want to.




(file #46868)
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Additional Item Attachment:

File name: bug56232.cset                  Size:1 KB
    <https://savannah.gnu.org/file/bug56232.cset?file_id=46868>



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