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meanvar.hh
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1/* -*- mia-c++ -*-
2 *
3 * This file is part of MIA - a toolbox for medical image analysis
4 * Copyright (c) Leipzig, Madrid 1999-2017 Gert Wollny
5 *
6 * MIA is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with MIA; if not, see <http://www.gnu.org/licenses/>.
18 *
19 */
20
21
22#ifndef mia_core_meanvar_hh
23#define mia_core_meanvar_hh
24
25#include <map>
26#include <cmath>
27#include <mia/core/defines.hh>
28
30
41template <typename ForwardIterator>
42std::pair<double, double> mean_var(ForwardIterator begin, ForwardIterator end)
43{
44 std::pair<double, double> result;
45 result.first = 0.0;
46 result.second = 0.0;
47 size_t n = 0;
48
49 while (begin != end) {
50 const double help = *begin;
51 result.first += help;
52 result.second += help * help;
53 ++n;
54 ++begin;
55 }
56
57 if (n > 0)
58 result.first /= n;
59
60 if (n > 1)
61 result.second = sqrt((result.second - n * result.first * result.first) / (n - 1));
62 else
63 result.second = 0.0;
64
65 return result;
66}
67
69
70#endif
#define NS_MIA_BEGIN
conveniance define to start the mia namespace
Definition: defines.hh:33
#define NS_MIA_END
conveniance define to end the mia namespace
Definition: defines.hh:36
std::pair< double, double > mean_var(ForwardIterator begin, ForwardIterator end)
Definition: meanvar.hh:42