00001 /*!@file BPnnet/BPneuron.C Back Prop Neuron class */ 00002 00003 // //////////////////////////////////////////////////////////////////// // 00004 // The iLab Neuromorphic Vision C++ Toolkit - Copyright (C) 2001 by the // 00005 // University of Southern California (USC) and the iLab at USC. // 00006 // See http://iLab.usc.edu for information about this project. // 00007 // //////////////////////////////////////////////////////////////////// // 00008 // Major portions of the iLab Neuromorphic Vision Toolkit are protected // 00009 // under the U.S. patent ``Computation of Intrinsic Perceptual Saliency // 00010 // in Visual Environments, and Applications'' by Christof Koch and // 00011 // Laurent Itti, California Institute of Technology, 2001 (patent // 00012 // pending; application number 09/912,225 filed July 23, 2001; see // 00013 // http://pair.uspto.gov/cgi-bin/final/home.pl for current status). // 00014 // //////////////////////////////////////////////////////////////////// // 00015 // This file is part of the iLab Neuromorphic Vision C++ Toolkit. // 00016 // // 00017 // The iLab Neuromorphic Vision C++ Toolkit is free software; you can // 00018 // redistribute it and/or modify it under the terms of the GNU General // 00019 // Public License as published by the Free Software Foundation; either // 00020 // version 2 of the License, or (at your option) any later version. // 00021 // // 00022 // The iLab Neuromorphic Vision C++ Toolkit is distributed in the hope // 00023 // that it will be useful, but WITHOUT ANY WARRANTY; without even the // 00024 // implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR // 00025 // PURPOSE. See the GNU General Public License for more details. // 00026 // // 00027 // You should have received a copy of the GNU General Public License // 00028 // along with the iLab Neuromorphic Vision C++ Toolkit; if not, write // 00029 // to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, // 00030 // Boston, MA 02111-1307 USA. // 00031 // //////////////////////////////////////////////////////////////////// // 00032 // 00033 // Primary maintainer for this file: Philip Williams <plw@usc.edu> 00034 // $HeadURL: svn://isvn.usc.edu/software/invt/trunk/saliency/src/BPnnet/BPneuron.C $ 00035 // $Id: BPneuron.C 4786 2005-07-04 02:18:56Z itti $ 00036 // 00037 00038 #include "BPnnet/BPneuron.H" 00039 #include <math.h> 00040 00041 // ###################################################################### 00042 BPneuron::BPneuron( void ) 00043 { 00044 delta = 0.0; 00045 weightedInputSum = 0.0; 00046 activationLevel = 0.0; 00047 } 00048 00049 // ###################################################################### 00050 BPneuron::~BPneuron() 00051 { } 00052 00053 // ###################################################################### 00054 void BPneuron::assignInput( double input ) 00055 { 00056 weightedInputSum = input; 00057 activationLevel = sigmoidFunction(weightedInputSum); 00058 } 00059 00060 // ###################################################################### 00061 double BPneuron::calcOutputDelta( double target ) 00062 { 00063 double difference = target - activationLevel; 00064 double f1 = derivSigmoidFunction(weightedInputSum); 00065 delta = difference * f1; 00066 return difference; 00067 } 00068 00069 // ###################################################################### 00070 void BPneuron::calcHiddenDelta( double weightedDeltaSum ) 00071 { 00072 double f1 = derivSigmoidFunction(weightedInputSum); 00073 delta = weightedDeltaSum * f1; 00074 } 00075 00076 // ###################################################################### 00077 double BPneuron::getDelta( void ) 00078 { 00079 return delta; 00080 } 00081 00082 // ###################################################################### 00083 double BPneuron::getActivationLevel( void ) 00084 { 00085 return activationLevel; 00086 } 00087 00088 // ###################################################################### 00089 double BPneuron::sigmoidFunction( const double x ) 00090 { return 1.0 / (1.0 + exp(- x)); } 00091 00092 // ###################################################################### 00093 double BPneuron::derivSigmoidFunction( const double x ) 00094 { 00095 double eS = exp( - x ); 00096 double dF = 1.0 + eS; 00097 return eS / (dF * dF); 00098 } 00099 00100 00101 // ###################################################################### 00102 /* So things look consistent in everyone's emacs... */ 00103 /* Local Variables: */ 00104 /* indent-tabs-mode: nil */ 00105 /* End: */
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