[SciPy-user] Fourier-sine transform with SciPy
Lubos Vrbka
lists@vrbka....
Fri Jun 6 12:47:58 CDT 2008
anne, thanks for detailed discussion (and sorry for accidentally
replying directly to you instead to list)!
> Note that the sine transform only works on odd functions, so either
> your input data should have f_k = f_{N-k} or you are representing only
> half the values, i.e., N is twice the number of data points you have.
> This too is somewhere a proper sine transform would help, if we had
> it.
well, the original function itself is neither even nor odd, since it is
defined only in the interval <0, +inf>. at certain point in the
derivation, the original function is multiplied by the r or k variable,
so it might actually be odd. the sine comes from the fact that the
original function is actually radially symmetric. i think i will have to
have a look into that an check the result.
hopefully the last question. how is it with the 'normalization
constants' for the dft? from theory it should be T/N for FT and 1/T for
iFT, but different packages treat this differently (for example fftw
does not use them and it has to be done afterwards 'manually') - how is
it in case of scipy.fft?
best,
lubos
--
Lubos _@_"
http://www.lubos.vrbka.net
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