1 // -*- C++ -*- 2 3 // Copyright (C) 2005-2020 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the terms 7 // of the GNU General Public License as published by the Free Software 8 // Foundation; either version 3, or (at your option) any later 9 // version. 10 11 // This library is distributed in the hope that it will be useful, but 12 // WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 // General Public License for more details. 15 16 // You should have received a copy of the GNU General Public License 17 // along with this library; see the file COPYING3. If not see 18 // <http://www.gnu.org/licenses/>. 19 20 21 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 22 23 // Permission to use, copy, modify, sell, and distribute this software 24 // is hereby granted without fee, provided that the above copyright 25 // notice appears in all copies, and that both that copyright notice 26 // and this permission notice appear in supporting documentation. None 27 // of the above authors, nor IBM Haifa Research Laboratories, make any 28 // representation about the suitability of this software for any 29 // purpose. It is provided "as is" without express or implied 30 // warranty. 31 32 /** 33 * @file sample_variance.hpp 34 * Contains a function for calculating a sample variance 35 */ 36 37 #ifndef PB_DS_SAMPLE_VAR_HPP 38 #define PB_DS_SAMPLE_VAR_HPP 39 40 #include <list> 41 #include <numeric> 42 #include <math.h> 43 #include <iterator> 44 45 namespace __gnu_pbds 46 { 47 namespace test 48 { 49 namespace detail 50 { 51 #define PB_DS_VTYPE typename std::iterator_traits<It>::value_type 52 53 template<typename It> 54 PB_DS_VTYPE sample_variance(It b,It e,PB_DS_VTYPE sm)55 sample_variance(It b, It e, PB_DS_VTYPE sm) 56 { 57 PB_DS_VTYPE ss = 0; 58 size_t num_res = 0; 59 60 while (b != e) 61 { 62 const PB_DS_VTYPE d =* b - sm; 63 ss += d* d; 64 ++num_res; 65 ++b; 66 } 67 68 if (num_res == 1) 69 return 0; 70 71 return ::sqrt(ss / (num_res - 1)); 72 } 73 74 #undef PB_DS_VTYPE 75 76 } // namespace detail 77 } // namespace test 78 } // namespace __gnu_pbds 79 80 #endif 81 82