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- /* 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 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.
- *
- * 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 "gsl__config.h"
- #include "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 */
- }
- }
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