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## Re: FFT output changes depending on row column vector

**From**: |
Miroslaw Kwasniak |

**Subject**: |
Re: FFT output changes depending on row column vector |

**Date**: |
Tue, 14 Apr 2009 10:52:38 +0200 |

**User-agent**: |
Mutt/1.5.9i |

On Tue, Apr 14, 2009 at 12:38:51PM +1000, Keith Bannister wrote:
>* 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. *
Yes, it does ;)
>* 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')')*
^^^
look here
Operator "'" does conjugate (Hermitian) transpose.
If you want only plain transpose use ".'" :
x=exp(2*pi()*I()*4*[1:32]/32);sumsq(fft(x) - fft(x.').'),[maxv, maxi]
= max(abs(fft(x))),[maxv, maxi] = max(abs(fft(x.').'))
ans = 0
maxv = 32
maxi = 5
maxv = 32
maxi = 5