[SciPy-user] fftw3 wrappers
Lars Friedrich
lfriedri at imtek.de
Wed Aug 8 02:41:31 EDT 2007
Hi David,
thank you for your answer.
David Cournapeau wrote:
> Mmh, sorry, I missed that you were interested in multi dimensional fft,
> this may explain the result. For 1d, fftw3 wrappers are almost always
> faster than numpy, but not for multi dimensional
Maybe I just did not tell before... I thought this would not make any
difference.
> What does scipy.show_config() tells you ?
...
fftw2_info:
NOT AVAILABLE
fftw3_info:
NOT AVAILABLE
...
> in my experience, scipy's fftw3 wrappers may or may not be faster than
> numpy for multi dimensional fft, depending on your architecture (eg
> Pentium 4 vs Pentium m vs Core Duo). This will change in the future,
> because the problem is on scipy's side, not on fftw3 (fftw by itself is
> certainly faster than what you get using numpy).
>
> If I were you, this is what I would do:
> - first, check whether you are really using fftw3 (using show_config)
> - if you are, then maybe you can try with fftw2 instead of fftw3:
> install fftw2 on your computer, and then rebuild scipy with FFTW3=None,
> eg: FFTW3=None python setup.py build (you can check whether fftw2 is
> picked instead of fftw3 by running first FFTW3 python setup.py config).
> - if this is ok for you, you may try the Intel MKL instead. I have
> never used it, but heard it is pretty efficient.
>
> fftw2 has a pretty good chance of working better than fftw3 now because
> it is more efficiently used by scipy. Hopefully, this will change soon
> (there is a bit some work needed to improve the wrappers efficiency
> wise: I am working on it).
I tend to wait for full fftw3-support... maybe I can help you? I started
with checking out http://svn.scipy.org/svn/scipy/trunk, is this the
right step?
Lars
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