UnaryHardSlopeVariable.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:
// 
//  1. Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
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/* *******************************************************      
   * $Id: UnaryHardSlopeVariable.h,v 1.2 2004/04/27 16:03:35 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#ifndef UnaryHardSlopeVariable_INC
#define UnaryHardSlopeVariable_INC

#include "UnaryVariable.h"

namespace PLearn {
using namespace std;


// output is 0 for input < left, 1 for input > right, and linear in between.
class UnaryHardSlopeVariable: public UnaryVariable
{
  typedef UnaryVariable inherited;

protected:
  real left;
  real right;
  real inv_slope; // 1/(right-left)

public:
  UnaryHardSlopeVariable() {}
  UnaryHardSlopeVariable(Variable* input,real l=-1,real r=1);

  PLEARN_DECLARE_OBJECT(UnaryHardSlopeVariable);
  static void declareOptions(OptionList &ol);

  virtual void build();

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

protected:
  void build_();
};

DECLARE_OBJECT_PTR(UnaryHardSlopeVariable);

inline Var unary_hard_slope(Var v, real l=-1, real r=1)
{ return new UnaryHardSlopeVariable(v,l,r); }

} // end of namespace PLearn

#endif 

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