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- /* statistics/quantiles_source.c
- *
- * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 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 3 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 ;
- }
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