[Octave-bug-tracker] [bug #63281] bsxfun fails to preserve sparse output for some functions

[Nicholas Jankowski]

Follow-up Comment #16, bug #63281 (project octave):

in the interest of restoring some performance gain of avoiding bsxfun and
maybe preserving the sparseness:

looking for example at center.m, instead of the current:

## FIXME: Use bsxfun, rather than broadcasting, until broadcasting
##        supports diagonal and sparse matrices (Bugs #41441, #35787).
y = bsxfun (@minus, x, mean (x, dim));
## y = x - mean (x, dim);   # automatic broadcasting


would something like this be acceptable?: 


try
  y = x - mean (x, dim);   # automatic broadcasting
catch err
  if any (strcmp (typeinfo (sparse (x)), ...
                  {"sparse matrix", "diagonal matrix"}))
    ##  y = bsxfun (@minus, x, mean (x, dim)); faster, but loses sparseness
    y = bsxfun(@(x,y) x-y, x, mean(x, dim)); # preserves sparseness
  else
    rethrow(err);
  endif
end_try_catch



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