UnaryHardSlopeVariable.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: UnaryHardSlopeVariable.cc,v 1.2 2004/04/27 16:03:35 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "UnaryHardSlopeVariable.h"
#include "Var_operators.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(UnaryHardSlopeVariable, 
                        "Hard slope function whose Var input is only the argument of the function.", 
                        "Maps x (elementwise) to 0 if x<left, 1 if x>right, and linear in between otherwise.");

UnaryHardSlopeVariable::UnaryHardSlopeVariable(Variable* input,real l,real r) 
  : inherited(input, input->length(), input->width()) ,
    left(l), right(r), inv_slope(1.0/(r-l))
{}

void
UnaryHardSlopeVariable::build()
{
    inherited::build();
    build_();
}

void
UnaryHardSlopeVariable::build_()
{
    inv_slope = (1.0 / (right - 1));
}

void
UnaryHardSlopeVariable::declareOptions(OptionList &ol)
{
    declareOption(ol, "left", &UnaryHardSlopeVariable::left, OptionBase::buildoption, "");
    declareOption(ol, "right", &UnaryHardSlopeVariable::right, OptionBase::buildoption, "");
    inherited::declareOptions(ol);
}

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


void UnaryHardSlopeVariable::fprop()
{
  int l = nelems();
  real* inputptr = input->valuedata;
  real* ptr = valuedata;
  for(int i=0; i<l; i++)
    *ptr++ = hard_slope(*inputptr++,left,right);
}


void UnaryHardSlopeVariable::bprop()
{
  int l = nelems();
  real* inputgradientptr = input->gradientdata;
  real* gradientptr = gradientdata;
  real* valueptr = valuedata;
  for(int i=0; i<l; i++)
  {
    real x = *valueptr++;
    if (x>left)
      if (x<right)
        *inputgradientptr++ += *gradientptr++ * inv_slope;
  }
}


} // end of namespace PLearn

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