[SciPy-dev] FFT docstrings (was: Scipy Tutorial (and updating it))

jh@physics.uc... jh@physics.uc...
Wed Dec 17 12:18:11 CST 2008


Joe: 

> I added the helper routines and defined the time and frequency domains
> near the top (and took out similar text near the bottom), fixed some
> commas, etc.

Tom:

> Looks good.  I didn't like the parentheses "(each gets exactly half
> the spectrum) in the discussion on real transforms", I think it is too
> easy to misunderstand (as I did on first reading).

Ok, but I think we need to tell them that the amplitudes from fft each
have half the value of the output of rfft, because the fft output
includes the set of redundant frequencies, which get summed in the
real case.  Maybe say just that.

Joe: 

> The zero channel of np.fft(a) is
> the mean, not the energy.

Tom:

> Well -- A[0], according to the definition in the first equation, is
> simply the sum of all the values in the input vector (since k == 0,
> all the exponentials are == 1).  I would not call that the mean.

You're right, it's the sum.  I was brought up on a 1/N normalization.

--jh--


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