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2D FFT

Dear friends,

  does anyone have or know of a 2D discrete real->complex and back FFT
routine for Pascal/Delphi?

Best regards,

  Ditlev

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Re:2D FFT


Quote
Ditlev Egeskov Brodersen wrote in message <35E1D2A6.62273...@imsb.au.dk>...
>  does anyone have or know of a 2D discrete real->complex and back FFT
>routine for Pascal/Delphi?

You might want to take a look at the links on the Numerical Methods page of
the Delphi Math Functions Pages in my Computer Lab.  You'll want the section
"Fourier Transforms, FFTs, Spectral Analysis."

efg
_________________________________________
efg's Computer Lab:  http://infomaster.net/external/efg

Earl F. Glynn                 E-Mail:  EarlGl...@att.net
MedTech Research Corporation, Lenexa, KS  USA

Re:2D FFT


Ditlev Egeskov Brodersen <d...@imsb.au.dk> wrote:

Quote
>  does anyone have or know of a 2D discrete real->complex and back FFT
>routine for Pascal/Delphi?

Check out the signal processing library at
http://developer.intel.com.

A delphi interface unit for the SPL is available from
http://home.t-online.de/home/Robert.Rossmair/

Cheers,

Glenn

Re:2D FFT


In article <35E1D2A6.62273...@imsb.au.dk>,
  Ditlev Egeskov Brodersen <d...@imsb.au.dk> wrote:

Quote
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> Dear friends,

>   does anyone have or know of a 2D discrete real->complex and back FFT
> routine for Pascal/Delphi?

         Sounds like you already have a 1-d FFT working. If so you
can use it to concoct a 2-d FFT.

         Psuedocode: let's say RowFFT is a procedure that takes a
2-d square array and replaces each row by its 1-d FFT. Say Transpose
swaps columns and rows. Then you can do a 2-d FFT like so

procedure 2dFFT(Data: T2dSquareArray);
begin
  RowFFT(Data);
  Transpose(Data);
  RowFFT(Data);
  Transpose(Data);
end;

(Um, that either gives the right answer or requires that all the
elements in Data be multiplied by a certain constant, depending
on exactly how your FFT's are "normalized".)

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Re:2D FFT


Quote
Ditlev Egeskov Brodersen wrote:
>   does anyone have or know of a 2D discrete real->complex and back FFT
> routine for Pascal/Delphi?

You can get a pretty fast complex-to-complex 1-D FFT component from
www.lohninger.com.  To do a 2-D DFT, replace each row of your
matrix with its DFT, then replace each column in the resulting
matrix with _its_ DFT. Voila.

--
Ewan Macpherson <emacp...@umich.edu>
Kresge Hearing Research Institute
http://www-personal.umich.edu/~emacpher/

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