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convolution.h File Reference

#include <algorithm>
#include "fftw3.h"
#include "fft/support.h"

Go to the source code of this file.

Namespaces
namespace	FFT

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Detailed Description

Copyright (c) 2004, Sylvain Paris and Francois Sillion
All rights reserved.

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    contributors may be used to endorse or promote products derived
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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This file contains useful functions to compute a convolution between two 2D functions. The code is based on FFTW (http://www.fftw.org/), a lot of magical numbers are explained on the web site. The system is set to make as many optimizations as possible and then it saves them in a file to reuse them. Therefore when a new data size is used, it takes some extra time at the first run.

Here is an example:

  // Array_2D has function members:
  //    x_size(), y_size(), resize(unsigned,unsigned)
  
  Array_2D<double> source,kernel,result;

  // ...
  // Some code to fill source and kernel with data.
  // !!! They must be of the same size.
  // ...

  // Wisdom data will be read and saved in the file "wisdom.fftw".
  // If the file does not exists, it will be created.
  FFT::Support::set_wisdom_file("wisdom.fftw");
  FFT::Support s(source.x_size(),source.y_size());

  // The following line is where the computation actually occurs.
  FFT::convolve(source,kernel,&result,s);

  // result is resized and now contains source*kernel.
  
  // If some convolutions are needed with the same data size,
  // the support s can be reused.

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