1 /* statistics/mean_source.c
2 *
3 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Jim Davies, Brian Gough
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 3 of the License, or (at
8 * your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 */
19
20 double
FUNCTION(gsl_stats,mean)21 FUNCTION (gsl_stats, mean) (const BASE data[], const size_t stride, const size_t size)
22 {
23 /* Compute the arithmetic mean of a dataset using the recurrence relation
24 mean_(n) = mean(n-1) + (data[n] - mean(n-1))/(n+1) */
25
26 long double mean = 0;
27 size_t i;
28
29 for (i = 0; i < size; i++)
30 {
31 mean += (data[i * stride] - mean) / (i + 1);
32 }
33
34 return mean;
35 }
36