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: MinVariable.cc 6438 2006-11-16 15:01:40Z chapados $ 00040 * This file is part of the PLearn library. 00041 ******************************************************* */ 00042 00043 #include "ArgminVariable.h" 00044 #include "ElementAtPositionVariable.h" 00045 #include "MinVariable.h" 00046 00047 namespace PLearn { 00048 using namespace std; 00049 00050 00053 PLEARN_IMPLEMENT_OBJECT( 00054 MinVariable, 00055 "Variable which returns the minimum value of its (single) input", 00056 "This Variable always has a size of 1 element:\n" 00057 "\n" 00058 " value(0,0) = min_i input[i]\n" 00059 "\n" 00060 "where input[i] is the i-th element of its input variable\n" 00061 "(dimensionality does not matter; it's viewed as a long vector)."); 00062 00063 MinVariable::MinVariable(Variable* input) 00064 : inherited(input, 1, 1) {} 00065 00066 00067 void MinVariable::recomputeSize(int& l, int& w) const 00068 { l=1; w=1; } 00069 00070 void MinVariable::fprop() 00071 { 00072 real minval = input->valuedata[0]; 00073 for(int i=1; i<input->nelems(); i++) 00074 { 00075 real val = input->valuedata[i]; 00076 if(val<minval) 00077 minval = val; 00078 } 00079 valuedata[0] = minval; 00080 } 00081 00082 00083 void MinVariable::bprop() 00084 { 00085 real minval = valuedata[0]; 00086 for(int i=0; i<input->nelems(); i++) 00087 { 00088 if(input->valuedata[i]==minval) 00089 input->gradientdata[i] += gradientdata[0]; 00090 } 00091 } 00092 00093 00094 void MinVariable::symbolicBprop() 00095 { 00096 input->accg(new ElementAtPositionVariable(g, argmin(input), input->length(), input->width())); 00097 } 00098 00099 00100 00101 } // end of namespace PLearn 00102 00103 00104 /* 00105 Local Variables: 00106 mode:c++ 00107 c-basic-offset:4 00108 c-file-style:"stroustrup" 00109 c-file-offsets:((innamespace . 0)(inline-open . 0)) 00110 indent-tabs-mode:nil 00111 fill-column:79 00112 End: 00113 */ 00114 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :