SignVariable.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: SignVariable.cc,v 1.5 2004/04/27 16:02:26 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "SignVariable.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(SignVariable,
                        "sign(x) = 1 if x>0, -1 if x<0, 0 if x=0, all done element by element.",
                        "NO HELP");

SignVariable::SignVariable(Variable* input) 
  : inherited(input, input->length(), input->width())
{}

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

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


// no gradients almost everywhere
void SignVariable::bprop()
{}


// no gradients almost everywhere
void SignVariable::symbolicBprop()
{}



} // end of namespace PLearn

---