SumSquareVariable.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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//  1. Redistributions of source code must retain the above copyright
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/* *******************************************************      
   * $Id: SumSquareVariable.cc,v 1.6 2004/04/27 16:02:26 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "SumSquareVariable.h"
#include "Var_operators.h"
//#include "Var_utils.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(SumSquareVariable,
                        "ONE LINE DESCR",
                        "NO HELP");

SumSquareVariable::SumSquareVariable(Variable* input)
  : inherited(input, 1, 1) {}

void SumSquareVariable::recomputeSize(int& l, int& w) const
{ l=1; w=1; }

void SumSquareVariable::fprop()
{
  int n=input->nelems();
  *valuedata= 0;
  for(int i=0; i<n; i++)
    *valuedata+= input->valuedata[i]*input->valuedata[i];
}


void SumSquareVariable::bprop()
{
  int n=input->nelems();
  for(int i=0; i<n; i++)
    input->gradientdata[i]+= 2.0 * input->valuedata[i] * *gradientdata;
}


void SumSquareVariable::symbolicBprop()
{
  input->accg(2.0 * (g*input));
}



} // end of namespace PLearn

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