PlusConstantVariable.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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/* *******************************************************      
   * $Id: PlusConstantVariable.cc,v 1.6 2004/04/27 15:59:16 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "PlusConstantVariable.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(PlusConstantVariable,
                        "Adds a scalar constant to a matrix var",
                        "NO HELP");

PlusConstantVariable::PlusConstantVariable(Variable* input, real c)
  : inherited(input, input->length(), input->width()), cst(c) 
{}


void
PlusConstantVariable::declareOptions(OptionList &ol)
{
    declareOption(ol, "cst", &PlusConstantVariable::cst, OptionBase::buildoption, "");
    inherited::declareOptions(ol);
}

void PlusConstantVariable::recomputeSize(int& l, int& w) const
{
    if (input) {
        l = input->length();
        w = input->width();
    } else
        l = w = 0;
}

void PlusConstantVariable::fprop()
{
  for(int k=0; k<nelems(); k++)
    valuedata[k] = input->valuedata[k] + cst;
}


void PlusConstantVariable::bprop()
{
  for(int k=0; k<nelems(); k++)
    input->gradientdata[k] += gradientdata[k];
}


void PlusConstantVariable::symbolicBprop()
{
  input->accg(g);
}


// R(x+c) = R(x)
void PlusConstantVariable::rfprop()
{
  if (rValue.length()==0) resizeRValue();
  for(int k=0; k<nelems(); k++)
    rvaluedata[k] = input->rvaluedata[k];
}



} // end of namespace PLearn

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