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

[Pearu Peterson]

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.

Pearu