[SciPy-user] fftw, scipy ("old") install

Pearu Peterson pearu at scipy.org
Mon Oct 17 04:41:09 CDT 2005

On Mon, 17 Oct 2005, Arnd Baecker wrote:

> Hi,
> it seems that I failed with fftw on the opteron ;-) -
> scipy fft is (much) slower than the Numeric one
> (see output below).
> I installed fftw via::
>  tar xzf ../Sources/fftw-3.0.1.tar.gz
>  cd fftw-3.0.1/
>  ./configure CFLAGS=-fPIC  --prefix=$PHOME
>  make
>  make install

The old scipy.fftpack supports only fftw2. I have a patch for fftw3 
somewhere. I'll apply it as soon as I'll get a chance to work on fftpack.

> Reconsidering this after seeing the poor performance
> shows that, `nm _fftpack.so` gives me no symbols  related to fftw.

Yes, _fftpack.so should contain Fortran fftpack when fftw (v2) library is 
not available.

> And for future builds:
> Is there a way to check (on the python level) which fft is used
> *after* the installation?

Normally it should be unnecessary. However, scipy building scripts install 
config.py (old scipy) or __config__.py (newscipy) files containing the 
system information used in building scipy.


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