PLearn 0.1
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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: LogSoftmaxVariable.cc 8847 2008-04-21 20:49:49Z tihocan $ 00040 * This file is part of the PLearn library. 00041 ******************************************************* */ 00042 00043 #include "LogSoftmaxVariable.h" 00044 00045 namespace PLearn { 00046 using namespace std; 00047 00048 00051 PLEARN_IMPLEMENT_OBJECT( 00052 LogSoftmaxVariable, 00053 "Compute the logarithm of the softmax of its input.", 00054 "This is more stable than combinining a softmax and a logarithm." 00055 ); 00056 00058 // LogSoftmaxVariable // 00060 LogSoftmaxVariable::LogSoftmaxVariable(Variable* input, bool call_build_): 00061 inherited(input, input->length(), input->width(), call_build_) 00062 { 00063 if (call_build_) 00064 build_(); 00065 } 00066 00068 // build // 00070 void LogSoftmaxVariable::build() 00071 { 00072 inherited::build(); 00073 build_(); 00074 } 00075 00077 // build_ // 00079 void LogSoftmaxVariable::build_() 00080 { 00081 // Nothing to do here. 00082 } 00083 00084 void LogSoftmaxVariable::recomputeSize(int& l, int& w) const 00085 { 00086 if (input) { 00087 l = input->length(); 00088 w = input->width(); 00089 } else 00090 l = w = 0; 00091 } 00092 00093 void 00094 LogSoftmaxVariable::fprop() 00095 { 00096 log_softmax(input->value, value); 00097 } 00098 00099 00100 void 00101 LogSoftmaxVariable::bprop() 00102 { 00103 for (int i = 0; i < input->nelems(); ++i) { 00104 real sum = 0.; 00105 for (int k = 0; k < nelems(); ++k) 00106 sum += gradientdata[k]; 00107 input->gradientdata[i] += gradientdata[i] - sum * safeexp(valuedata[i]); 00108 } 00109 } 00110 00111 00112 void 00113 LogSoftmaxVariable::bbprop() 00114 { 00115 PLERROR("LogSofmaxVariable::bbprop() not implemented"); 00116 } 00117 00118 00119 void 00120 LogSoftmaxVariable::symbolicBprop() 00121 { 00122 PLERROR("LogSofmaxVariable::symbolicBprop() not implemented"); 00123 } 00124 00125 00126 00127 } // end of namespace PLearn 00128 00129 00130 /* 00131 Local Variables: 00132 mode:c++ 00133 c-basic-offset:4 00134 c-file-style:"stroustrup" 00135 c-file-offsets:((innamespace . 0)(inline-open . 0)) 00136 indent-tabs-mode:nil 00137 fill-column:79 00138 End: 00139 */ 00140 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :