[SciPy-User] how to interpret numpy.fft.fftfreq output?

Francesco Stablum stablum@gmail....
Mon Oct 12 12:59:46 CDT 2009


Hello,

I am doing the fft of a wave file (44100 Hz) with some kind of success.
I have a problem: I have to display the frequencies amounts and I have
to calculate which frequency corresponds to the indexes of the result
of the fft. I am actually using the fftfreq function in this way:

fft.fftfreq(5120,d=1.0/22050.0)

(5120 is number of frames).

The result is that the second half of the array is negative. I have
seen in the documentation that it is normal... why?
I would expect to have an array like this: [0,5, .. , 22045,2050].

How should interpret the output of fftfreq?

thanks for the attention,
Francesco Stablum

-- 
The generation of random numbers is too important to be left to chance
- Robert R. Coveyou


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