CutAboveThresholdVariable.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

// Redistribution and use in source and binary forms, with or without
// 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: CutAboveThresholdVariable.cc,v 1.6 2004/04/27 15:59:16 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "CutAboveThresholdVariable.h"
#include "IsAboveThresholdVariable.h"
#include "Var_operators.h"

namespace PLearn {
using namespace std;


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

CutAboveThresholdVariable::CutAboveThresholdVariable(Variable* input, real the_threshold)
  : inherited(input, input->length(), input->width()), threshold(the_threshold) 
{}


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

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

void CutAboveThresholdVariable::fprop()
{
  for(int i=0; i<nelems(); i++)
    {
      real val = input->valuedata[i];
      valuedata[i] = val>threshold ?threshold :val;
    }
}


void CutAboveThresholdVariable::bprop()
{
  for(int i=0; i<nelems(); i++)
    if(input->valuedata[i]<=threshold)        
      input->gradientdata[i] += gradientdata[i];
}


void CutAboveThresholdVariable::symbolicBprop()
{
  input->accg(g * (input<=threshold));
}



} // end of namespace PLearn

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