source: trunk/yat/classifier/GaussianKernelFunction.h @ 680

Last change on this file since 680 was 680, checked in by Jari Häkkinen, 15 years ago

Addresses #153. Introduced yat namespace. Removed alignment namespace. Clean up of code.

  • 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) 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 "KernelFunction.h"
28#include "DataLookup1D.h"
29
30#include <cmath>
31
32namespace theplu {
33namespace yat {
34namespace classifier {
35
36  ///
37  /// Class for Gaussian kernel calculations.
38  ///
39 
40  class GaussianKernelFunction : public KernelFunction
41  {
42   
43  public:
44    ///
45    /// Constructor taking the sigma_ , i.e. the width of the Gaussian,as
46    /// input. Default is sigma_ = 1.
47    ///
48    GaussianKernelFunction(double = 1);
49   
50    ///
51    ///Destructor
52    ///
53       virtual ~GaussianKernelFunction(void) {};
54   
55    ///
56    /// returning the scalar product of two vectors in feature space using the
57    /// Gaussian kernel. @return \f$ exp(-(x - y)^{2}/\sigma^2) \f$ \n
58    ///
59    double operator()(const DataLookup1D& x,
60                      const DataLookup1D& y) const; 
61
62    /**
63       \f$ \exp(-d^2/\sigma^2) \f$ where \f$ d^2 = \sum w_y(x_i-y_i)^2
64       / \sum w_y * N \f$
65     **/
66    double operator()(const DataLookup1D& x,
67                      const DataLookupWeighted1D& y) const; 
68
69    /**
70       \f$ \exp(-d^2/\sigma^2) \f$ where \f$ d^2 = \sum w_xw_y(x_i-y_i)^2
71       / \sum w_xw_y * N \f$
72     **/
73    double operator()(const DataLookupWeighted1D& x,
74                      const DataLookupWeighted1D& y) const; 
75
76  private:
77    double sigma2_;
78
79  }; // class GaussianKernelFunction
80
81}}} // of namespace classifier, yat, and theplu
82
83#endif
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