PLearn 0.1
EqualVariable.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: EqualVariable.cc 4291 2005-10-21 15:15:01Z tihocan $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "EqualVariable.h"
00044 #include "EqualScalarVariable.h"
00045 
00046 namespace PLearn {
00047 using namespace std;
00048 
00049 
00050 
00051 
00054 PLEARN_IMPLEMENT_OBJECT(EqualVariable,
00055                         "A scalar var;  equal 1 if input1==input2, 0 otherwise",
00056                         "NO HELP");
00057 
00058 EqualVariable::EqualVariable(Variable* input1, Variable* input2)
00059     : inherited(input1, input2, 1,1)
00060 {
00061     build_();
00062 }
00063 
00064 void
00065 EqualVariable::build()
00066 {
00067     inherited::build();
00068     build_();
00069 }
00070 
00071 void
00072 EqualVariable::build_()
00073 {
00074     if (input1 && input2) {
00075         if (input1->length() != input2->length() || input1->width() != input2->width())
00076             PLERROR("IN EqualVariable(Variable* input1, Variable* input2) input1 and input2 must have the same size");
00077     }
00078 }
00079 
00080   
00081 void EqualVariable::recomputeSize(int& l, int& w) const
00082 { l=1; w=1; }
00083 
00084 void EqualVariable::fprop()
00085 {
00086     bool equal=true;
00087     for (int i=0; i<nelems(); i++)
00088         equal = equal && 
00089                 fast_exact_is_equal(input1->valuedata[i],input2->valuedata[i]);
00090     valuedata[0]=equal;
00091 }
00092 
00093 
00094 // not really differentiable (zero gradient almost everywhere)
00095 void EqualVariable::bprop() {}
00096 
00097 void EqualVariable::symbolicBprop() {}
00098 
00099 Var isequal(Var v1, Var v2)
00100 {
00101     if(v2->isScalar())
00102         return new EqualScalarVariable(v1,v2);
00103     else if(v1->isScalar())
00104         return new EqualScalarVariable(v2,v1);
00105     else
00106         return new EqualVariable(v1,v2);
00107 }
00108 
00109 
00110 } // end of namespace PLearn
00111 
00112 
00113 /*
00114   Local Variables:
00115   mode:c++
00116   c-basic-offset:4
00117   c-file-style:"stroustrup"
00118   c-file-offsets:((innamespace . 0)(inline-open . 0))
00119   indent-tabs-mode:nil
00120   fill-column:79
00121   End:
00122 */
00123 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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