From help-request at octave dot org Fri Dec 17 12:14:32 2004
Subject: Re: fft source [was "Very important"]
From: Joerg <joerg-at-ibk at web dot de>
To: Octave Newsgroup <help at octave dot org>
CC: Geraint Paul Bevan <g dot bevan at eng dot gla dot ac dot uk>
Date: Fri, 17 Dec 2004 19:18:49 +0100

Geraint Paul Bevan wrote:
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> Hash: SHA1
> 
> eman mohamed wrote:
> | Hi ;
> |
> | Can you please tell me where i can find the fft.m , i need the source
> | code for fft soon please , as it is very important to me .
> |
> | If you have the source code please send it to me .
> |
> | Thanks alot for your help in advance .
> |
> 
> 
> Firstly, you should probably use more specific titles when posting to
> mailing lists. "Very important" looks like a virus-laden or spam message.
> 
> Secondly, all of the sources to Octave are available from the download
> page at www.octave.org.
> 
> 
> If you type "which fft" at the Octave prompt, you will see that fft is a
> builtin function. It is not implemented as an m-file.
> 
> There are numerous Octave files which have some part to play in the
> implementation of FFT:
> 
> $ find /usr/local/src/octave/octave -name "*fft*"
> /usr/local/src/octave/octave/libcruft/fftpack
> /usr/local/src/octave/octave/libcruft/fftpack/cfftb.f
> /usr/local/src/octave/octave/libcruft/fftpack/cfftb1.f
> /usr/local/src/octave/octave/libcruft/fftpack/cfftf.f
> /usr/local/src/octave/octave/libcruft/fftpack/cfftf1.f
> /usr/local/src/octave/octave/libcruft/fftpack/cffti.f
> /usr/local/src/octave/octave/libcruft/fftpack/cffti1.f
> /usr/local/src/octave/octave/libcruft/fftpack/fftpack.doc
> /usr/local/src/octave/octave/liboctave/oct-fftw.cc
> /usr/local/src/octave/octave/liboctave/oct-fftw.h
> /usr/local/src/octave/octave/scripts/signal/fftconv.m
> /usr/local/src/octave/octave/scripts/signal/fftfilt.m
> /usr/local/src/octave/octave/scripts/signal/fftshift.m
> /usr/local/src/octave/octave/src/DLD-FUNCTIONS/fft.cc
> /usr/local/src/octave/octave/src/DLD-FUNCTIONS/fft2.cc
> /usr/local/src/octave/octave/src/DLD-FUNCTIONS/fftn.cc
> /usr/local/src/octave/octave/src/DLD-FUNCTIONS/fftw_wisdom.cc
> /usr/local/src/octave/octave/test/octave.test/signal/fft-1.m
> /usr/local/src/octave/octave/test/octave.test/signal/fft2-1.m
> /usr/local/src/octave/octave/test/octave.test/signal/ifft-1.m
> /usr/local/src/octave/octave/test/octave.test/signal/ifft2-1.m
> 
> All of these files can be obtained in a tarball of via CVS. See
> http://www.octave.org/download
> 
> If you look at fft.cc, you will see that a call to the fourier()
> function in the NDArray code occurs,
> 
> try:
> $ find /usr/local/src/octave/octave -name "*NDArray*"
> 
> However, the actual FFT itself is performed using standard libraries. If
> you have the FFTW3 library installed on your system, Octave will use
> that. If not, it will use FFTPACK (the code to which is contained in the
> octave/libcruft directory).
> 
if you are interested where fftw3 comes from:

http://www.fftw.org/

here you find everything ...
Jörg

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