[Octave-bug-tracker] [bug #63791] movfun - high intermediate memory use for moderate data input resulting in out of memory errors

[Rik]

Follow-up Comment #27, bug #63791 (project octave):

@Nicholas: The error registers nearly instantaneously.  When Octave asks the
operating system for a large chunk of memory, and the operating system says
no, then Octave stops immediately.

For example:


tic;
try
  z = zeros (2^53,1);
end_try_catch
toc
Elapsed time is 0.0363941 seconds.


So, 36 milliseconds.

I suggested a general strategy for functions like mean() in one of the bug
reports and that suggestion was taken up by the author of the statistics
package.  That used permute/do function/ipermute rather than for loops over
extra dimensions.

The case of movfun() is different because it creates data.  For delaunayn, I
think a different solution is needed.  The issue there seems to be that det()
operates only on dimensions 1&2 (area) and so you need a for loop over all the
possible planes.  That really might require moving that bit of code to C++.


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