source: branches/0.4-stable/yat/classifier/KernelFunction.h @ 1392

#ifndef _theplu_yat_classifier_kernel_function_
#define _theplu_yat_classifier_kernel_function_

// $Id$

/*
  Copyright (C) 2003 Peter Johansson
  Copyright (C) 2004 Jari Häkkinen, Peter Johansson
  Copyright (C) 2005 Peter Johansson
  Copyright (C) 2006, 2007 Jari Häkkinen, Peter Johansson

  This file is part of the yat library, http://dev.thep.lu.se/yat

  The yat library is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.

  The yat library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

namespace theplu {
namespace yat {
namespace classifier {
  class DataLookup1D;
  class DataLookupWeighted1D;

  ///
  /// @brief Interface class calculating elements in Kernel.
  ///
  class KernelFunction 
  {
    
  public:
    ///
    /// Constructor
    ///    
    KernelFunction(void) {};

    ///
    /// Destructor
    ///
    virtual ~KernelFunction(void) {};
    
    ///
    /// @return scalar product of two vector in feature space.
    ///
    virtual double operator()(const DataLookup1D&,
                              const DataLookup1D&) const = 0; 
    
    ///
    /// @return scalar product of two vector in feature space.
    ///
    virtual double operator()(const DataLookup1D&,
                              const DataLookupWeighted1D&) const = 0; 
    
    ///
    /// @return scalar product of two vector in feature space.
    ///
    inline double operator()(const DataLookupWeighted1D& vec_w,
                             const DataLookup1D& vec) const 
    { return this->operator()(vec,vec_w); } 
    
    ///
    /// @return scalar product of two vector in feature space.
    ///
    virtual double operator()(const DataLookupWeighted1D&,
                              const DataLookupWeighted1D&) const = 0; 
    
  }; // class KernelFunction

}}} // of namespace classifier, yat, and theplu

#endif