RowAtPositionVariable.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:
// 
//  1. Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
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//  2. Redistributions in binary form must reproduce the above copyright
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//     documentation and/or other materials provided with the distribution.
// 
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// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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/* *******************************************************      
   * $Id: RowAtPositionVariable.cc,v 1.5 2004/04/27 16:03:35 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "RowAtPositionVariable.h"
#include "VarRowVariable.h"

namespace PLearn {
using namespace std;


PLEARN_IMPLEMENT_OBJECT(RowAtPositionVariable,
                        "Variables positionned inside a larger zero variable ...",
                        "NO HELP");

RowAtPositionVariable::RowAtPositionVariable(Variable* input1, Variable* input2, int the_length)
  : inherited(input1, input2, the_length, input1->width()), length_(the_length)
{
    build_();
}

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

void
RowAtPositionVariable::build_()
{
    if (input1 && input2) {
        if(!input1->isRowVec())
            PLERROR("In RowAtPositionVariable: input1 must be a single row");
        if(!input2->isScalar())
            PLERROR("In RowAtPositionVariable: position must be a scalar");
    }
}

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

void RowAtPositionVariable::recomputeSize(int& l, int& w) const
{
    l=length_;
    if (input1)
        w = input1->width();
    else
        w = 0;
}

void RowAtPositionVariable::fprop()
{
  value.clear();
  int i = (int)input2->valuedata[0];
  matValue(i) << input1->value;
}


void RowAtPositionVariable::bprop()
{
  int i = (int)input2->valuedata[0];
  input1->gradient += matGradient(i);
}


void RowAtPositionVariable::symbolicBprop()
{
  input1->accg(new VarRowVariable(g,input2));
}


void RowAtPositionVariable::rfprop()
{
  if (rValue.length()==0) resizeRValue();
  //rValue.clear();
  int i = (int)input2->valuedata[0];
  matRValue(i) << input1->rValue;
}



} // end of namespace PLearn

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