| /* interpolation/bsearch.h |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2004 Gerard Jungman |
| * |
| * 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. |
| */ |
| |
| /* Author: G. Jungman |
| */ |
| #ifndef __GSL_INTERP_BSEARCH_H__ |
| #define __GSL_INTERP_BSEARCH_H__ |
| |
| |
| /* Perform a binary search of an array of values. |
| * |
| * The parameters index_lo and index_hi provide an initial bracket, |
| * and it is assumed that index_lo < index_hi. The resulting index |
| * is guaranteed to be strictly less than index_hi and greater than |
| * or equal to index_lo, so that the implicit bracket [index, index+1] |
| * always corresponds to a region within the implicit value range of |
| * the value array. |
| * |
| * Note that this means the relationship of 'x' to x_array[index] |
| * and x_array[index+1] depends on the result region, i.e. the |
| * behaviour at the boundaries may not correspond to what you |
| * expect. We have the following complete specification of the |
| * behaviour. |
| * Suppose the input is x_array[] = { x0, x1, ..., xN } |
| * if ( x == x0 ) then index == 0 |
| * if ( x > x0 && x <= x1 ) then index == 0, and sim. for other interior pts |
| * if ( x == xN ) then index == N-1 |
| * if ( x > xN ) then index == N-1 |
| * if ( x < x0 ) then index == 0 |
| */ |
| size_t |
| gsl_interp_bsearch( |
| const double x_array[], double x, |
| size_t index_lo, |
| size_t index_hi |
| ); |
| |
| |
| #ifdef HAVE_INLINE |
| extern |
| inline |
| size_t |
| gsl_interp_bsearch( |
| const double x_array[], double x, |
| size_t index_lo, |
| size_t index_hi |
| ) |
| { |
| size_t ilo = index_lo; |
| size_t ihi = index_hi; |
| while(ihi > ilo + 1) { |
| size_t i = (ihi + ilo)/2; |
| if(x_array[i] > x) |
| ihi = i; |
| else |
| ilo = i; |
| } |
| |
| return ilo; |
| } |
| #endif /* HAVE_INLINE */ |
| |
| |
| #endif /* __GSL_INTERP_BSEARCH_H__ */ |
