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

#include "UnequalConstantVariable.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(UnequalConstantVariable,
                        "A scalar var;  equal 1 if input1!=c, 0 otherwise",
                        "NO HELP");

UnequalConstantVariable::UnequalConstantVariable(Variable* input1, real c_)
  : inherited(input1, input1->length(), input1->width()), c(c_)
{}

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

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

void UnequalConstantVariable::fprop()
{
  for(int i=0; i<nelems(); i++)
    valuedata[i] = (input->valuedata[i] != c);
}


// not really differentiable (zero gradient almost everywhere)
void UnequalConstantVariable::bprop() {}

void UnequalConstantVariable::symbolicBprop() {}



} // end of namespace PLearn

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