[Numpy-discussion] numpy.fft, yet again

Eric Firing efiring@hawaii....
Mon Jul 12 17:04:01 CDT 2010


On 07/12/2010 11:43 AM, David Goldsmith wrote:
>  >From the docstring:
>
> "A[0] contains the zero-frequency term (the mean of the signal)"
>
> And yet, consistent w/ the definition given in the docstring (and
> included w/ an earlier email), the code gives, e.g.:
>
>  >>> import numpy as np
>  >>> x = np.ones((16,)); x
> array([ 1.,  1.,  1.,  1.,  1.,  1.,  1.,  1.,  1.,  1.,  1.,  1.,  1.,
>          1.,  1.,  1.])
>  >>> y = np.fft.fft(x); y
> array([ 16.+0.j,   0.+0.j,   0.+0.j,   0.+0.j,   0.+0.j,   0.+0.j,
>           0.+0.j,   0.+0.j,   0.+0.j,   0.+0.j,   0.+0.j,   0.+0.j,
>           0.+0.j,   0.+0.j,   0.+0.j,   0.+0.j])
>
> i.e., the zero-th term is the sum, not the mean (which, again, is
> consistent w/ the stated defining formula).
>
> So, same ol', same ol': bug in the doc (presumably) or bug in the code?

Bug in the doc.  Good catch.  "mean" is correct for the ifft, not for 
the fft.

Eric

>
> DG
>
>
>
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