[Octave-bug-tracker] [bug #64733] IFFT returns wrong data for dNDArray input

[Markus Mützel]

Follow-up Comment #4, bug #64733 (project octave):

I'm not sure what the intensions of the original author were. I can only
guess.
It is true that for the "end usage" in Octave, there is probably always a
allocation for the result that is separate from the input. I'm not sure what
is happening for inplace operations like `x = ifft(x);`.
Technically, the functions in liboctave could also be used by code outside the
Octave interpreter. In that case, in-place operation might also be of
advantage. (I don't know how far our support for usage outside Octave goes
though.)

I agree that changing how we use this function in liboctinterp could also work
around this issue. The issue in liboctave would still remain though (if it
*is* an issue).

I was considering this change for the stable branch (because it should have
low risk of breaking things and wouldn't change the API). 
I was thinking about introducing new preprocessor macros similar to
OCTAVE_LOCAL_BUFFER that would allow extending the scope of a buffer. If that
works, it could allow reducing the current code duplication in this area. That
change would need to go to the default branch though.

I haven't fully explored how these functions are used though. So, please let
me know if I'm missing something.



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