| /* statistics/quantiles_source.c |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000 Jim Davies, Brian Gough |
| * |
| * This program 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 2 of the License, or (at |
| * your option) any later version. |
| * |
| * This program 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 this program; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| */ |
| |
| |
| double |
| FUNCTION(gsl_stats,quantile_from_sorted_data) (const BASE sorted_data[], |
| const size_t stride, |
| const size_t n, |
| const double f) |
| { |
| const double index = f * (n - 1) ; |
| const size_t lhs = (int)index ; |
| const double delta = index - lhs ; |
| double result; |
| |
| if (n == 0) |
| return 0.0 ; |
| |
| if (lhs == n - 1) |
| { |
| result = sorted_data[lhs * stride] ; |
| } |
| else |
| { |
| result = (1 - delta) * sorted_data[lhs * stride] + delta * sorted_data[(lhs + 1) * stride] ; |
| } |
| |
| return result ; |
| } |
