[Numpy-discussion] fft help
burlen.loring at gmail.com
Thu Dec 29 12:32:55 EST 2011
hmmph, I used both fftn and fft2, they both produce the same result. Is
there a restriction on the dimension of the input? power of 2 or some such?
On 12/29/2011 07:21 AM, Torgil Svensson wrote:
> This is because fft computes one-dimensional transforms (on each row).
> Try fft2 instead.
> fft(a, n=None, axis=-1)
> Compute the one-dimensional discrete Fourier Transform.
> fft2(a, s=None, axes=(-2, -1))
> Compute the 2-dimensional discrete Fourier Transform
> fftn(a, s=None, axes=None)
> Compute the N-dimensional discrete Fourier Transform.
> On Wed, Dec 28, 2011 at 10:05 PM, Burlen Loring<burlen.loring at gmail.com> wrote:
>> I have an image I need to do an fft on, I tried numpy.fft but results are
>> not what I expected, and differ from matlab.
>> My input image is a weird size, 5118x1279, I think numpy fft is not liking it. In
>> numpy the fft appears to be computed multiple times and tiled across the
>> output image. In other words the pattern I see in matlab fft is tiled
>> repeatedly over numpy fft output. Any idea on what I'm doing wrong?
>> you can see repeated pattern in the top panel of this image which also has
>> the input in the bottom panel.
>> http://old.nabble.com/file/p33047057/fft_uex.png fft_uex.png
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