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: SoftmaxVariable.cc 8848 2008-04-21 20:51:04Z tihocan $ 00040 * This file is part of the PLearn library. 00041 ******************************************************* */ 00042 00043 #include "SoftmaxVariable.h" 00044 00045 namespace PLearn { 00046 using namespace std; 00047 00048 00051 PLEARN_IMPLEMENT_OBJECT( 00052 SoftmaxVariable, 00053 "Softmax of its input variable.", 00054 "" 00055 ); 00056 00057 SoftmaxVariable::SoftmaxVariable(Variable* input) 00058 : inherited(input, input->length(), input->width()) 00059 {} 00060 00061 void SoftmaxVariable::recomputeSize(int& l, int& w) const 00062 { 00063 if (input) { 00064 l = input->length(); 00065 w = input->width(); 00066 } else 00067 l = w = 0; 00068 } 00069 00070 void SoftmaxVariable::fprop() 00071 { 00072 softmax(input->value,value); 00073 } 00074 00075 00076 void SoftmaxVariable::bprop() 00077 { 00078 for(int i=0; i<input->nelems(); i++) 00079 { 00080 real vali = valuedata[i]; 00081 for(int k=0; k<nelems(); k++) 00082 { 00083 if(k!=i) 00084 input->gradientdata[i] -= gradientdata[k]*vali*valuedata[k]; 00085 else 00086 input->gradientdata[i] += gradientdata[i]*vali*(1.-vali); 00087 } 00088 } 00089 } 00090 00091 00092 void SoftmaxVariable::bbprop() 00093 { 00094 PLERROR("SofmaxVariable::bbprop() not implemented"); 00095 } 00096 00097 00098 void SoftmaxVariable::symbolicBprop() 00099 { 00100 PLERROR("SofmaxVariable::symbolicBprop() not implemented"); 00101 } 00102 00103 00104 // R{ s_i = exp(x_i) / sum_j exp(x_j) } = (s_i(1-s_i) - sum_{k!=i} s_i s_k) R(s_i) = s_i ((1-s_i) - sum_{k!=i} s_k) R(s_i) 00105 void SoftmaxVariable::rfprop() 00106 { 00107 if (rValue.length()==0) resizeRValue(); 00108 for(int i=0; i<input->nelems(); i++) 00109 { 00110 real vali = valuedata[i]; 00111 rvaluedata[i] = vali * (1 - vali) * input->rvaluedata[i]; 00112 } 00113 } 00114 00115 00116 00117 } // end of namespace PLearn 00118 00119 00120 /* 00121 Local Variables: 00122 mode:c++ 00123 c-basic-offset:4 00124 c-file-style:"stroustrup" 00125 c-file-offsets:((innamespace . 0)(inline-open . 0)) 00126 indent-tabs-mode:nil 00127 fill-column:79 00128 End: 00129 */ 00130 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :