| /* sys/gsl_compare.c |
| * |
| * Copyright (C) 2002 Gert Van den Eynde |
| * |
| * 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. |
| * |
| * Based on fcmp 1.2.2 Copyright (c) 1998-2000 Theodore C. Belding |
| * University of Michigan Center for the Study of Complex Systems |
| * Ted.Belding@umich.edu |
| * |
| */ |
| |
| #include <config.h> |
| #include <gsl/gsl_sys.h> |
| #include <math.h> |
| |
| int |
| gsl_fcmp (const double x1, const double x2, const double epsilon) |
| { |
| int exponent; |
| double delta, difference; |
| |
| /* Find exponent of largest absolute value */ |
| |
| { |
| double max = (fabs (x1) > fabs (x2)) ? x1 : x2; |
| |
| frexp (max, &exponent); |
| } |
| |
| /* Form a neighborhood of size 2 * delta */ |
| |
| delta = ldexp (epsilon, exponent); |
| |
| difference = x1 - x2; |
| |
| if (difference > delta) /* x1 > x2 */ |
| { |
| return 1; |
| } |
| else if (difference < -delta) /* x1 < x2 */ |
| { |
| return -1; |
| } |
| else /* -delta <= difference <= delta */ |
| { |
| return 0; /* x1 ~=~ x2 */ |
| } |
| } |
| |