NegCrossEntropySigmoidVariable.h

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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
//     notice, this list of conditions and the following disclaimer.
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/* *******************************************************      
   * $Id: NegCrossEntropySigmoidVariable.h,v 1.4 2004/04/27 15:58:16 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#ifndef NegCrossEntropySigmoidVariable_INC
#define NegCrossEntropySigmoidVariable_INC

#include "BinaryVariable.h"

namespace PLearn {
using namespace std;


class NegCrossEntropySigmoidVariable: public BinaryVariable
{
  typedef BinaryVariable inherited;
protected:
  
  real regularizer;
  
public:
  NegCrossEntropySigmoidVariable() {}
  NegCrossEntropySigmoidVariable(Variable* netout, Variable* target, real regularizer_ = 0.0);

  PLEARN_DECLARE_OBJECT(NegCrossEntropySigmoidVariable);

  virtual void build();

  virtual void recomputeSize(int& l, int& w) const;
  virtual void fprop();
  virtual void bprop();
  void setRegularizer(real r);

protected:
    void build_();
};

DECLARE_OBJECT_PTR(NegCrossEntropySigmoidVariable);

inline Var stable_cross_entropy(Var linear_output, Var target)
{
  return new NegCrossEntropySigmoidVariable(linear_output, target);
}

} // end of namespace PLearn

#endif 

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