[SciPy-user] Using fftpack.diff

[Neilen Marais]

Hi

I'm trying to get the DFT of the derivative of a real valued periodic
signal. If I have the time domain
signal in ts (where one period is stored in ts), I do:

fs = scipy.fftpack.fft(ts)
dfs = scipy.fftpack.diff(fs)
dts = scipy.fftpack.ifft(dfs)

However dts seems to be almost purely imaginary whereas ts is purely real.
I haven't done DFT related stuff for a while, am I misunderstanding
completely?

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