source: trunk/yat/classifier/GaussianKernelFunction.h @ 1437

Last change on this file since 1437 was 1437, checked in by Peter, 13 years ago

merge patch release 0.4.2 to trunk. Delta 0.4.2-0.4.1

  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date ID
File size: 2.2 KB
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1#ifndef _theplu_yat_classifier_gaussian_kernel_function_
2#define _theplu_yat_classifier_gaussian_kernel_function_
3
4// $Id$
5
6/*
7  Copyright (C) 2004, 2005, 2006, 2007 Jari Häkkinen, Peter Johansson
8
9  This file is part of the yat library, http://dev.thep.lu.se/yat
10
11  The yat library is free software; you can redistribute it and/or
12  modify it under the terms of the GNU General Public License as
13  published by the Free Software Foundation; either version 2 of the
14  License, or (at your option) any later version.
15
16  The yat library is distributed in the hope that it will be useful,
17  but WITHOUT ANY WARRANTY; without even the implied warranty of
18  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19  General Public License for more details.
20
21  You should have received a copy of the GNU General Public License
22  along with this program; if not, write to the Free Software
23  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
24  02111-1307, USA.
25*/
26
27#include "KernelFunction.h"
28
29#include <cmath>
30
31namespace theplu {
32namespace yat {
33namespace classifier {
34
35  class DataLookup1D;
36
37  ///
38  /// @brief Class for Gaussian kernel calculations.
39  ///
40 
41  class GaussianKernelFunction : public KernelFunction
42  {
43   
44  public:
45    ///
46    /// Constructor taking the sigma_ , i.e. the width of the Gaussian,as
47    /// input. Default is sigma_ = 1.
48    ///
49    GaussianKernelFunction(double = 1);
50   
51    ///
52    ///Destructor
53    ///
54       virtual ~GaussianKernelFunction(void) {};
55   
56    ///
57    /// returning the scalar product of two vectors in feature space using the
58    /// Gaussian kernel. @return \f$ exp(-(x - y)^{2}/\sigma^2) \f$ \n
59    ///
60    double operator()(const DataLookup1D& x,
61                      const DataLookup1D& y) const; 
62
63    /**
64       \f$ \exp(-d^2/\sigma^2) \f$ where \f$ d^2 = \sum w_y(x_i-y_i)^2
65       / \sum w_y * N \f$
66     **/
67    double operator()(const DataLookup1D& x,
68                      const DataLookupWeighted1D& y) const; 
69
70    /**
71       \f$ \exp(-d^2/\sigma^2) \f$ where \f$ d^2 = \sum w_xw_y(x_i-y_i)^2
72       / \sum w_xw_y * N \f$
73     **/
74    double operator()(const DataLookupWeighted1D& x,
75                      const DataLookupWeighted1D& y) const; 
76
77  private:
78    double sigma2_;
79
80  }; // class GaussianKernelFunction
81
82}}} // of namespace classifier, yat, and theplu
83
84#endif
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