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FFT output changes depending on row column vector
From: |
Keith Bannister |
Subject: |
FFT output changes depending on row column vector |
Date: |
Tue, 14 Apr 2009 12:38:51 +1000 |
Hi,
Please don't flame me, but I'm having a really weird issue.
I was hoping taking the FFT of a row would give the the same result as
the transpose of the fft of a column. The FFT of a column seems to be
some weird reversed version of what I expect.
Here's some code:
octave2.9:85> version
ans = 2.9.9
octave2.9:81> x = exp(2*pi()*I()*4*[1:32]/32);
octave2.9:101> sumsq(fft(x) - fft(x')')
ans = 2048.0
octave2.9:102> [maxv, maxi] = max(abs(fft(x)))
maxv = 32
maxi = 5
octave2.9:103> [maxv, maxi] = max(abs(fft(x')'))
maxv = 32
maxi = 29
The documentation (and google AFAIK) don't mention this. Do I have a
duff installation or something?
--
Keith Bannister
- FFT output changes depending on row column vector,
Keith Bannister <=