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/* This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT.
* See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details.
* Author(s): Clément Maria
*
* Copyright (C) 2014 Inria
*
* Modification(s):
* - YYYY/MM Author: Description of the modification
*/
#ifndef DISTANCE_FUNCTIONS_H_
#define DISTANCE_FUNCTIONS_H_
#include <gudhi/Debug_utils.h>
#include <boost/range/metafunctions.hpp>
#include <boost/range/size.hpp>
#include <cmath> // for std::sqrt
#include <type_traits> // for std::decay
#include <iterator> // for std::begin, std::end
#include <utility>
namespace Gudhi {
/** @file
* @brief Global distance functions
*/
/** @brief Compute the Euclidean distance between two Points given by a range of coordinates. The points are assumed to
* have the same dimension. */
class Euclidean_distance {
public:
// boost::range_value is not SFINAE-friendly so we cannot use it in the return type
template< typename Point >
typename std::iterator_traits<typename boost::range_iterator<Point>::type>::value_type
operator()(const Point& p1, const Point& p2) const {
auto it1 = std::begin(p1);
auto it2 = std::begin(p2);
typedef typename boost::range_value<Point>::type NT;
NT dist = 0;
for (; it1 != std::end(p1); ++it1, ++it2) {
GUDHI_CHECK(it2 != std::end(p2), "inconsistent point dimensions");
NT tmp = *it1 - *it2;
dist += tmp*tmp;
}
GUDHI_CHECK(it2 == std::end(p2), "inconsistent point dimensions");
using std::sqrt;
return sqrt(dist);
}
template< typename T >
T operator() (const std::pair< T, T >& f, const std::pair< T, T >& s) const {
T dx = f.first - s.first;
T dy = f.second - s.second;
using std::sqrt;
return sqrt(dx*dx + dy*dy);
}
};
} // namespace Gudhi
#endif // DISTANCE_FUNCTIONS_H_
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