source: trunk/yat/classifier/GaussianKernelFunction.h @ 676

Last change on this file since 676 was 675, checked in by Jari Häkkinen, 15 years ago

References #83. Changing project name to yat. Compilation will fail in this revision.

  • Property svn:eol-style set to native
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File size: 2.2 KB
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1#ifndef _theplu_classifier_gaussian_kernel_function_
2#define _theplu_classifier_gaussian_kernel_function_
3
4// $Id$
5
6/*
7  Copyright (C) The authors contributing to this file.
8
9  This file is part of the yat library, http://lev.thep.lu.se/trac/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 "yat/classifier/KernelFunction.h"
28#include "yat/classifier/DataLookup1D.h"
29
30#include <cmath>
31
32namespace theplu {
33namespace classifier {
34
35  ///
36  /// Class for Gaussian kernel calculations.
37  ///
38 
39  class GaussianKernelFunction : public KernelFunction
40  {
41   
42  public:
43    ///
44    /// Constructor taking the sigma_ , i.e. the width of the Gaussian,as
45    /// input. Default is sigma_ = 1.
46    ///
47    GaussianKernelFunction(double = 1);
48   
49    ///
50    ///Destructor
51    ///
52       virtual ~GaussianKernelFunction(void) {};
53   
54    ///
55    /// returning the scalar product of two vectors in feature space using the
56    /// Gaussian kernel. @return \f$ exp(-(x - y)^{2}/\sigma^2) \f$ \n
57    ///
58    double operator()(const DataLookup1D& x,
59                      const DataLookup1D& y) const; 
60
61    /**
62       \f$ \exp(-d^2/\sigma^2) \f$ where \f$ d^2 = \sum w_y(x_i-y_i)^2
63       / \sum w_y * N \f$
64     **/
65    double operator()(const DataLookup1D& x,
66                      const DataLookupWeighted1D& y) const; 
67
68    /**
69       \f$ \exp(-d^2/\sigma^2) \f$ where \f$ d^2 = \sum w_xw_y(x_i-y_i)^2
70       / \sum w_xw_y * N \f$
71     **/
72    double operator()(const DataLookupWeighted1D& x,
73                      const DataLookupWeighted1D& y) const; 
74
75  private:
76    double sigma2_;
77
78  }; // class GaussianKernelFunction
79
80}} // of namespace classifier and namespace theplu
81
82#endif
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