Steffen Müller > Math-FFTW-0.01 > Math::FFTW

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NAME ^

Math::FFTW - Perl interface to parts of the FFTW

SYNOPSIS ^

  use Math::FFTW;
  
  # should be evenly spaced in x
  my @ydata = ...; # with noise
  my $coefficients = Math::FFTW::fftw_dft_real2complex_1d(\@ydata);
  
  # $coefficients is ary ref. Contains the complex fourier
  # coefficients as [c1_real, c1_imaginary, c2_real, ..., cn_imaginary]
  
  # should give us the same data as we put in.
  my $same_y_data = Math::FFTW::fftw_idft_complex2real_1d($coefficients);
  
  # set all coefficients beyond the fiftieth to zero
  $_=0 for @{$coefficients}[100..$#$coefficients];
  # ==> should smooth our data
  
  my $smoothed = Math::FFTW::fftw_idft_complex2real_1d($coefficients);

DESCRIPTION ^

The recommended interface of this module may change. In that case, however, backwards compatible routines will be provided.

This is an interface to small parts of the FFTW library. Currently, only the forward and backward Discrete Fourier Transform of one-dimensional real data is supported.

If you need anything else, let me know. (And send a patch along if you like.)

INSTALLATION

You can install this module as you would install any other Perl/XS extension provided that the FFTW library and its headers are available and can be found by your compiler/linker.

Tested on Linux/x64.

EXPORT

None by default. The fftw_dft_real2complex_1d and fftw_idft_complex2real_1d subroutines can be exported on demand.

SUBROUTINES ^

fftw_dft_real2complex_1d

The forward DFT returns an array of N/2+1 complex fourier coefficients. The complex coefficients are returned as two reals each. (Real part, then imaginary part)

The returned array (reference) should have (N/2+1)*2 = N+2 elements.

fftw_idft_complex2real_1d

The backward, or inverse DFT returns data from a set of coefficients as returned by fftw_dft_real2complex_1d.

Given an array reference of N+2 elements as input, you should get an array (reference) of N elements in return.

SEE ALSO ^

http://www.fftw.org

AUTHOR ^

Steffen Müller, <tsee@>

COPYRIGHT AND LICENSE ^

Copyright (C) 2007 by Steffen Müller

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.6 or, at your option, any later version of Perl 5 you may have available.

The FFTW library is not contained in this package. Its copyright is held by Matteo Frigo and the MIT. It is distributed under the GNU General Public License.

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