PLearn 0.1
LogSumVariable.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: LogSumVariable.cc 6861 2007-04-09 19:04:15Z saintmlx $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "LogSumVariable.h"
00044 #include "SoftmaxVariable.h"
00045 #include "Var_operators.h"
00046 //#include "Var_utils.h"
00047 
00048 namespace PLearn {
00049 using namespace std;
00050 
00051 
00052 
00055 LogSumVariable::LogSumVariable(Variable* input)
00056     :UnaryVariable(input,1,1),input_softmax(input->nelems()) {}
00057 
00058 
00059 PLEARN_IMPLEMENT_OBJECT(LogSumVariable, "ONE LINE DESCR", "NO HELP");
00060 
00061 void LogSumVariable::recomputeSize(int& l, int& w) const
00062 { l=1; w=1; }
00063 
00064 
00065 
00066 
00067 
00068 
00069 
00070 
00071 void LogSumVariable::makeDeepCopyFromShallowCopy(CopiesMap& copies)
00072 {
00073     inherited::makeDeepCopyFromShallowCopy(copies);
00074     deepCopyField(input_softmax, copies);
00075 }
00076 
00077 
00078 void LogSumVariable::fprop()
00079 {
00080     valuedata[0] = logadd(input->value);
00081 }
00082 
00083 
00084 void LogSumVariable::bprop()
00085 {
00086     softmax(input->value,input_softmax);
00087     multiplyAcc(input->gradient, input_softmax,gradientdata[0]);
00088 }
00089 
00090 
00091 void LogSumVariable::symbolicBprop()
00092 {
00093     input->accg(g*softmax(input));
00094 }
00095 
00096 
00097 
00098 } // end of namespace PLearn
00099 
00100 
00101 /*
00102   Local Variables:
00103   mode:c++
00104   c-basic-offset:4
00105   c-file-style:"stroustrup"
00106   c-file-offsets:((innamespace . 0)(inline-open . 0))
00107   indent-tabs-mode:nil
00108   fill-column:79
00109   End:
00110 */
00111 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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