ConvolveVariable.cc

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// -*- C++ -*-

// PLearn (A C++ Machine Learning Library)
// Copyright (C) 1998 Pascal Vincent
// Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio, Rejean Ducharme and University of Montreal
// Copyright (C) 2001-2002 Nicolas Chapados, Ichiro Takeuchi, Jean-Sebastien Senecal
// Copyright (C) 2002 Xiangdong Wang, Christian Dorion

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// modification, are permitted provided that the following conditions are met:
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/* *******************************************************      
   * $Id: ConvolveVariable.cc,v 1.5 2004/04/27 16:02:26 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "ConvolveVariable.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(ConvolveVariable,
                        "A convolve var; equals convolve(input, mask)",
                        "NO HELP");

ConvolveVariable::ConvolveVariable(Variable* input, Variable* mask)
  : inherited(input, mask, input->length()-mask->length()+1, input->width()-mask->width()+1)
{}


void ConvolveVariable::recomputeSize(int& l, int& w) const
{
    if (input1 && input2) {
        l = input1->length() - input2->length() + 1;
        w = input1->width() - input2->width() + 1;
    } else
        l = w = 0;
}


void ConvolveVariable::fprop()
{
  convolve(input1->matValue, input2->matValue, matValue);
}


void ConvolveVariable::bprop()
{
  for(int i=0; i<length(); i++) // size of matGradient
    for(int j=0; j<width(); j++)
      {
        real* input1valueptr = input1->matValue[i]+j;
        real* input2valueptr = input2->matValue.data();
        
        real thisgradient = matGradient(i,j);
        real* input1gradientptr = input1->matGradient[i]+j;
        real* input2gradientptr = input2->matGradient.data();
        
        for(int l=0; l<input2->length(); l++,
              input1valueptr += input1->matValue.mod(), input2valueptr += input2->matValue.mod(),
              input1gradientptr += input1->matGradient.mod(), input2gradientptr += input2->matGradient.mod())
          for(int c=0; c<input2->width(); c++)
            {
              input1gradientptr[c] += thisgradient * input2valueptr[c];
              input2gradientptr[c] += thisgradient * input1valueptr[c];
            }
      }
}


void ConvolveVariable::symbolicBprop()
{ PLERROR("ConvolveVariable::symbolicBprop() not yet implemented"); }



} // end of namespace PLearn

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