00001 /*!@file BPnnet/BPneuron.H header for a back prop neuron */ 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.H $ 00035 // $Id: BPneuron.H 4786 2005-07-04 02:18:56Z itti $ 00036 // 00037 00038 #ifndef BPNEURON_H_DEFINED 00039 #define BPNEURON_H_DEFINED 00040 00041 //! neuron for a back prop neural net (BPnnet) 00042 class BPneuron { 00043 public: 00044 //! Constructor 00045 BPneuron(); 00046 00047 //! Destructor 00048 ~BPneuron(); 00049 00050 //! Assign given weighted input sum [S_j] and activation level 00051 /*! Activation Level a_j = f(S_j)*/ 00052 void assignInput(double input); 00053 00054 //! Calculate and set delta for output neurons 00055 /*! For output layer neurons; finds difference between output and 00056 target and multiplies by derivative of sigmoid function [delta_j = 00057 (t_j - a_j)*f'(S_j)] 00058 returns the difference [t_j - a_j] for RMS error calculation */ 00059 double calcOutputDelta(const double target); 00060 00061 //! Calculate and set delta for hidden neurons 00062 /*! For hidden layer neurons; compute hidden delta from weighted sum 00063 of output deltas [delta_j = sum_k(delta_k * w_kj)*f'(S_j)] 00064 returns delta_j */ 00065 void calcHiddenDelta(double weightedDeltaSum); 00066 00067 //! Return delta (error level) 00068 double getDelta(); 00069 00070 //! Return activation level 00071 double getActivationLevel(); 00072 00073 private: 00074 // Perform sigmoid function on x 00075 double sigmoidFunction(const double x); 00076 00077 // Perform first derivative of sigmoid function on x 00078 double derivSigmoidFunction(const double x); 00079 00080 double delta; // d_j 00081 double weightedInputSum; // a_j 00082 double activationLevel; // S_j 00083 }; 00084 00085 #endif 00086 00087 // ###################################################################### 00088 /* So things look consistent in everyone's emacs... */ 00089 /* Local Variables: */ 00090 /* indent-tabs-mode: nil */ 00091 /* End: */
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