PLearn 0.1
MinusVariable.cc
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00001 // -*- C++ -*-
00002 
00003 // PLearn (A C++ Machine Learning Library)
00004 // Copyright (C) 1998 Pascal Vincent
00005 // Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio, Rejean Ducharme and University of Montreal
00006 // Copyright (C) 2001-2002 Nicolas Chapados, Ichiro Takeuchi, Jean-Sebastien Senecal
00007 // Copyright (C) 2002 Xiangdong Wang, Christian Dorion
00008 
00009 // Redistribution and use in source and binary forms, with or without
00010 // modification, are permitted provided that the following conditions are met:
00011 // 
00012 //  1. Redistributions of source code must retain the above copyright
00013 //     notice, this list of conditions and the following disclaimer.
00014 // 
00015 //  2. Redistributions in binary form must reproduce the above copyright
00016 //     notice, this list of conditions and the following disclaimer in the
00017 //     documentation and/or other materials provided with the distribution.
00018 // 
00019 //  3. The name of the authors may not be used to endorse or promote
00020 //     products derived from this software without specific prior written
00021 //     permission.
00022 // 
00023 // THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
00024 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00025 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
00026 // NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00027 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00028 // TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00029 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00030 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00031 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00032 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00033 // 
00034 // This file is part of the PLearn library. For more information on the PLearn
00035 // library, go to the PLearn Web site at www.plearn.org
00036 
00037 
00038 /* *******************************************************      
00039  * $Id: MinusVariable.cc 6351 2006-10-25 19:05:45Z chapados $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "MinusVariable.h"
00044 #include "NegateElementsVariable.h"
00045 
00046 namespace PLearn {
00047 using namespace std;
00048 
00049 
00052 PLEARN_IMPLEMENT_OBJECT(MinusVariable,
00053                         "ONE LINE DESCR",
00054                         "NO HELP");
00055 
00056 MinusVariable::MinusVariable(Variable* input1, Variable* input2)
00057     : inherited(input1, input2, input1->length(), input1->width())
00058 {
00059     build_();
00060 }
00061 
00062 void
00063 MinusVariable::build()
00064 {
00065     inherited::build();
00066     build_();
00067 }
00068 
00069 void
00070 MinusVariable::build_()
00071 {
00072     if (input1 && input2) {
00073         if(input1->length()!=input2->length() || input1->width()!=input2->width())
00074             PLERROR("In MinusVariable: input1 and input2 must have exactly the same size");
00075     }
00076 }
00077 
00078 
00079 void MinusVariable::recomputeSize(int& l, int& w) const
00080 {
00081     if (input1) {
00082         l = input1->length();
00083         w = input1->width();
00084     } else
00085         l = w = 0;
00086 }
00087 
00088 void MinusVariable::fprop()
00089 {
00090     PLASSERT( input1 && input2 );
00091     PLASSERT( nelems() == input2->nelems() && nelems() == input2->nelems() );
00092     for(int k=0; k<nelems(); k++)
00093         valuedata[k] = input1->valuedata[k]-input2->valuedata[k];
00094 }
00095 
00096 
00097 void MinusVariable::bprop()
00098 {
00099     for(int k=0; k<nelems(); k++)
00100     {
00101         input1->gradientdata[k] += gradientdata[k];
00102         input2->gradientdata[k] -= gradientdata[k];
00103     }
00104 }
00105 
00106 
00107 void MinusVariable::bbprop()
00108 {
00109     if (input1->diaghessian.length()==0)
00110         input1->resizeDiagHessian();
00111     if (input2->diaghessian.length()==0)
00112         input2->resizeDiagHessian();
00113     for(int k=0; k<nelems(); k++)
00114     {
00115         input1->diaghessiandata[k] += diaghessiandata[k];
00116         input2->diaghessiandata[k] -= diaghessiandata[k];
00117     }
00118 }
00119 
00120 
00121 void MinusVariable::symbolicBprop()
00122 {
00123     input1->accg(g);
00124     input2->accg(new NegateElementsVariable(g));
00125 }
00126 
00127 
00128 } // end of namespace PLearn
00129 
00130 
00131 /*
00132   Local Variables:
00133   mode:c++
00134   c-basic-offset:4
00135   c-file-style:"stroustrup"
00136   c-file-offsets:((innamespace . 0)(inline-open . 0))
00137   indent-tabs-mode:nil
00138   fill-column:79
00139   End:
00140 */
00141 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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