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lms/src/third-party/knnl/euclidean_distance_function.hpp
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2016-04-14 12:53:29 +02:00

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/*
* Copyright (c) 2006, Seweryn Habdank-Wojewodzki
* Copyright (c) 2006, Janusz Rybarski
*
* All rights reserved.
*
* Redistribution and use in source and binary forms,
* with or without modification, are permitted provided
* that the following conditions are met:
*
* Redistributions of source code must retain the above
* copyright notice, this list of conditions and the
* following disclaimer.
*
* Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions
* and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS
* AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* e-mail: habdank AT gmail DOT com
* e-mail: janusz.rybarski AT gmail DOT com
*
* File created: Fri 14 Apr 2006 22:42:31 CEST
* Last modified: Wed 08 Aug 2007 18:21:06 CEST
*/
#ifndef EUCLIDEAN_DISTANCE_FUNCTION_HPP_INCLUDED
#define EUCLIDEAN_DISTANCE_FUNCTION_HPP_INCLUDED
#include <numeric>
#include "operators.hpp"
#include "basic_weak_distance_function.hpp"
#include "value_type.hpp"
/**
* \file euclidean_distance_function.hpp
* \brief File contains template class Euclidean_distance_function.
* \ingroup distance
*/
namespace distance
{
/**
* \addtogroup distance
*/
/*\@{*/
/**
* Euclidean_distance_function template class.
* \param Value_type is a type of values.
* \f[
* d (x,y) = \sum\limits_{i=0}^{N} cdot (x_i-y_i)^2
* \f]
*/
template
<
typename Value_type
>
class Euclidean_distance_function
: public Basic_weak_distance_function
<
Value_type,
Value_type
>
{
public:
/**
* Constructor.
*/
Euclidean_distance_function()
{}
/**
* Calculation function.
* \param x first input value for the function.
* \param y second input value for the function.
* \return square of the Euclidean distance function.
* \f[
* d (x,y) = \sum\limits_{i=0}^{N} cdot (x_i-y_i)^2
* \f]
*/
typename Value_type::value_type operator()
(
Value_type const & x,
Value_type const & y
) const
{
return
(
euclidean_distance_square
(
x.begin(),
x.end(),
y.begin(),
static_cast < typename Value_type::value_type const & > ( 0 )
)
);
}
private:
typedef typename Value_type::value_type inner_type;
/**
* Function calculates Euclidean distance between two containers.
* \param begin_1 is a begin iterator for the first container.
* \param end_1 is an end iterator for the first container.
* \param begin_2 is an begin iterator for the second container.
* \param init is an initial value.
* \result sqare of Euclidean distance.
*/
inner_type euclidean_distance_square
(
typename Value_type::const_iterator begin_1,
typename Value_type::const_iterator end_1,
typename Value_type::const_iterator begin_2,
inner_type const & init
) const
{
return ::std::inner_product
(
begin_1, end_1, begin_2,
static_cast < inner_type > ( init ),
::std::plus < inner_type >(),
::operators::compose_f_gxy_gxy
(
::std::multiplies < inner_type >(),
::std::minus < inner_type >()
)
);
}
};
/*\@}*/
} // namespace distance
#endif // EUCLIDEAN_DISTANCE_FUNCTION_HPP_INCLUDED