1 /* statistics/quantiles_source.c
3 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Jim Davies, Brian Gough
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.
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.
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.
22 FUNCTION(gsl_stats,quantile_from_sorted_data) (const BASE sorted_data[],
27 const double index = f * (n - 1) ;
28 const size_t lhs = (int)index ;
29 const double delta = index - lhs ;
37 result = sorted_data[lhs * stride] ;
41 result = (1 - delta) * sorted_data[lhs * stride] + delta * sorted_data[(lhs + 1) * stride] ;