1 /* interpolation/bsearch.h
3 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2004 Gerard Jungman
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 #ifndef __GSL_INTERP_BSEARCH_H__
23 #define __GSL_INTERP_BSEARCH_H__
26 /* Perform a binary search of an array of values.
28 * The parameters index_lo and index_hi provide an initial bracket,
29 * and it is assumed that index_lo < index_hi. The resulting index
30 * is guaranteed to be strictly less than index_hi and greater than
31 * or equal to index_lo, so that the implicit bracket [index, index+1]
32 * always corresponds to a region within the implicit value range of
35 * Note that this means the relationship of 'x' to x_array[index]
36 * and x_array[index+1] depends on the result region, i.e. the
37 * behaviour at the boundaries may not correspond to what you
38 * expect. We have the following complete specification of the
40 * Suppose the input is x_array[] = { x0, x1, ..., xN }
41 * if ( x == x0 ) then index == 0
42 * if ( x > x0 && x <= x1 ) then index == 0, and sim. for other interior pts
43 * if ( x == xN ) then index == N-1
44 * if ( x > xN ) then index == N-1
45 * if ( x < x0 ) then index == 0
49 const double x_array[], double x,
60 const double x_array[], double x,
65 size_t ilo = index_lo;
66 size_t ihi = index_hi;
67 while(ihi > ilo + 1) {
68 size_t i = (ihi + ilo)/2;
77 #endif /* HAVE_INLINE */
80 #endif /* __GSL_INTERP_BSEARCH_H__ */