[Numpy-discussion] FFT usage / consistency

Stéfan van der Walt stefan@sun.ac...
Tue Jul 29 07:45:31 CDT 2008


2008/7/29 Felix Richter <felix@physik3.uni-rostock.de>:
> I learned a few things in the meantime:
>
> In my installation, NumPy uses fftpack_lite while SciPy uses FFTW3. There are
> more test cases in SciPy which all pass. So I am confirmed my problem is a
> pure usage problem.
> One thing I was confused about is the fact that even if I calculate the
> function over a certain interval, I cannot tell FFT which interval this is,
> it will instead assume [0...n]. So actually I did not transform a Lorentz
> function centered at zero but rather centered at 500.
> Unfortunately, this solves only half of my problem, because I still cannot
> reproduce the exact FT. I'll ask for that on the SciPy list, this now seems
> more appropriate.

Felix,

Do your answers differ from the theory by a constant factor, or are
they completely unrelated?

Stéfan


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