[SciPy-user] test_fft, test_ifft results

Darren Dale dd55 at cornell.edu
Sun Dec 11 13:53:37 CST 2005

On Saturday 10 December 2005 5:57 pm, Darren Dale wrote:
> I have been wondering about the results of
> fftpack.basic.test_basic.test_fft, fftpack.basic.test_basic.test_fftn and
> fftpack.basic.test_basic.test_ifft. On my system, with scipy built against
> fftw2 or 3, ffts of complex input takes over 8 times as long as real input.

I would like to clarify this report. I thought that editing site.cfg to find 
fftw-2 would make scipy build against it, but this is not the case. One can 
build scipy with support for only fftw-2 by commenting out the fftw3 
dictionary in the fftw_info class in scipy/distutils/systeminfo.py. The 
performance of fft's for complex and real input are comparable if scipy is 
built with fftw-2 in this way.

According to some benchmarks posted at 
http://www.fftw.org/speed/p4-2.2GHz-gcc/ , version 3 should be faster than 
version 2. However, I haven't been able to build benchfft and test my own 
installation independent of scipy.


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