3 * Copyright (C) 2002 Gert Van den Eynde
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.
19 * Based on fcmp 1.2.2 Copyright (c) 1998-2000 Theodore C. Belding
20 * University of Michigan Center for the Study of Complex Systems
21 * Ted.Belding@umich.edu
26 #include <gsl/gsl_sys.h>
30 gsl_fcmp (const double x1, const double x2, const double epsilon)
33 double delta, difference;
35 /* Find exponent of largest absolute value */
38 double max = (fabs (x1) > fabs (x2)) ? x1 : x2;
40 frexp (max, &exponent);
43 /* Form a neighborhood of size 2 * delta */
45 delta = ldexp (epsilon, exponent);
49 if (difference > delta) /* x1 > x2 */
53 else if (difference < -delta) /* x1 < x2 */
57 else /* -delta <= difference <= delta */
59 return 0; /* x1 ~=~ x2 */