#ifndef theplu_yat_statistics_euclidean_distance_h #define theplu_yat_statistics_euclidean_distance_h // $Id: EuclideanDistance.h 1487 2008-09-10 08:41:36Z jari$ /* Copyright (C) 2007 Jari Häkkinen, Peter Johansson, Markus Ringnér Copyright (C) 2008 Peter Johansson, Markus Ringnér 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 3 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 yat. If not, see . */ #include "AveragerPair.h" #include "AveragerPairWeighted.h" #include "yat/utility/iterator_traits.h" #include namespace theplu { namespace yat { namespace statistics { /// /// @brief Calculates the Euclidean distance between two points /// given by elements of ranges. /// /// This class is modelling the concept \ref concept_distance. /// /// struct EuclideanDistance { /** \brief Calculates the Euclidean distance between elements of two ranges. If elements of both ranges are unweighted the distance is calculated as \f$\sqrt{\sum (x_i-y_i)^2 } \f$, where \f$x_i \f$ and \f$y_i \f$ are elements of the first and second range, respectively. If elements of one or both of ranges have weights the distance is calculated as \f$\sqrt{N \sum w_{x,i}w_{y,i}(x_i-y_i)^2/\sum w_{x,i}w_{y,i}} \f$, where \f$N \f$ is the number of elements in the two ranges and \f$w_x \f$ and \f$w_y \f$ are weights for the elements of the first and the second range, respectively. If the elements of one of the two ranges are unweighted, the weights for these elements are set to unity. */ template double operator() (Iter1 beg1,Iter1 end1, Iter2 beg2) const { return this->distance(beg1, end1, beg2, typename utility::weighted_if_any2::type()); } private: template double distance (Iter1 beg1,Iter1 end1, Iter2 beg2, utility::unweighted_iterator_tag) const { AveragerPair ap; add(ap,beg1,end1,beg2); return sqrt(ap.sum_squared_deviation()); } template double distance (Iter1 beg1,Iter1 end1, Iter2 beg2, utility::weighted_iterator_tag) const { AveragerPairWeighted ap; add(ap,beg1,end1,beg2); return sqrt(std::distance(beg1,end1)*ap.msd()); } }; }}} // of namespace statistics, yat, and theplu #endif