PLearn 0.1
IfThenElseVariable.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: IfThenElseVariable.cc 5876 2006-06-15 14:24:49Z chapados $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "IfThenElseVariable.h"
00044 #include "Var_utils.h"
00045 #include <plearn/math/TMat_maths.h>
00046 
00047 namespace PLearn {
00048 using namespace std;
00049 
00050 
00053 PLEARN_IMPLEMENT_OBJECT(
00054     IfThenElseVariable,
00055     "Variable that represents the element-wise IF-THEN-ELSE",
00056     "Variable that represents the element-wise IF-THEN-ELSE:\n"
00057     "- The first parent is the test (0 or different from 0)\n"
00058     "- The second parent is the value returned when the test is !=0,\n"
00059     "- The third parent is the value returned when the test is ==0,\n");
00060 
00061 IfThenElseVariable::IfThenElseVariable(Var IfVar, Var ThenVar, Var ElseVar)
00062     : inherited(IfVar & ThenVar & (VarArray)ElseVar,ThenVar->length(), ThenVar->width())
00063 {
00064     build_();
00065 }
00066 
00067 void
00068 IfThenElseVariable::build()
00069 {
00070     inherited::build();
00071     build_();
00072 }
00073 
00074 void
00075 IfThenElseVariable::build_()
00076 {
00077     if (varray.size()) {
00078         if (varray[1]->length() != varray[2]->length() || varray[1]->width() != varray[2]->width())
00079             PLERROR("In IfThenElseVariable: ElseVar and ThenVar must have the same size");
00080         if (!varray[0]->isScalar() && (varray[0]->length() != varray[1]->length() || varray[0]->width() != varray[1]->width()))
00081             PLERROR("In IfThenElseVariable: IfVar must either be a scalar or have the same size as ThenVar and ElseVar");
00082     }
00083 }
00084 
00085 void IfThenElseVariable::recomputeSize(int& l, int& w) const
00086 {
00087     if (varray.size()) {
00088         l = varray[1]->length();
00089         w = varray[1]->width();
00090     } else
00091         l = w = 0;
00092 }
00093 
00094 void IfThenElseVariable::fprop()
00095 {
00096     if(If()->isScalar())
00097     {
00098         bool test = !fast_exact_is_equal(If()->valuedata[0], 0);
00099         if (test)
00100             value << Then()->value;
00101         else
00102             value << Else()->value;
00103     }
00104     else
00105     {
00106         real* ifv = If()->valuedata;
00107         real* thenv = Then()->valuedata;
00108         real* elsev = Else()->valuedata;
00109         for (int k=0;k<nelems();k++)
00110         {
00111             if ( !fast_exact_is_equal(ifv[k], 0) )
00112                 valuedata[k]=thenv[k];
00113             else
00114                 valuedata[k]=elsev[k];
00115         }
00116     }
00117 }
00118 
00119 
00120 void IfThenElseVariable::bprop()
00121 {
00122     if(If()->isScalar())
00123     {
00124         if (!fast_exact_is_equal(If()->valuedata[0], 0))
00125             Then()->gradient += gradient;
00126         else
00127             Else()->gradient += gradient;
00128     }
00129     else
00130     {
00131         real* ifv = If()->valuedata;
00132         real* theng = Then()->gradientdata;
00133         real* elseg = Else()->gradientdata;
00134         for (int k=0;k<nelems();k++)
00135         {
00136             if ( !fast_exact_is_equal(ifv[k], 0)  )
00137                 theng[k] += gradientdata[k];
00138             else
00139                 elseg[k] += gradientdata[k];
00140         }
00141     }
00142 }
00143 
00144 
00145 void IfThenElseVariable::symbolicBprop()
00146 {
00147     Var zero(length(), width());
00148     Then()->accg(ifThenElse(If(), g, zero));
00149     Else()->accg(ifThenElse(If(), zero, g));
00150 }
00151 
00152 
00153 void IfThenElseVariable::rfprop()
00154 {
00155     if (rValue.length()==0) resizeRValue();
00156     if(If()->isScalar())
00157     {
00158         if (!fast_exact_is_equal(If()->valuedata[0], 0))
00159             rValue << Then()->rValue;
00160         else
00161             rValue << Else()->rValue;
00162     }
00163     else
00164     {
00165         real* ifv = If()->valuedata;
00166         real* rthenv = Then()->rvaluedata;
00167         real* relsev = Else()->rvaluedata;
00168         for (int k=0;k<nelems();k++)
00169         {
00170             if ( !fast_exact_is_equal(ifv[k], 0) )
00171                 rvaluedata[k]=rthenv[k];
00172             else
00173                 rvaluedata[k]=relsev[k];
00174         }
00175     }
00176 }
00177 
00178 
00179 
00180 } // end of namespace PLearn
00181 
00182 
00183 /*
00184   Local Variables:
00185   mode:c++
00186   c-basic-offset:4
00187   c-file-style:"stroustrup"
00188   c-file-offsets:((innamespace . 0)(inline-open . 0))
00189   indent-tabs-mode:nil
00190   fill-column:79
00191   End:
00192 */
00193 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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