1 /* integration/err.c
2 *
3 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Brian Gough
4 *
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.
9 *
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.
14 *
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.
18 */
19
20 #include <config.h>
21 #include <math.h>
22 #include <float.h>
23 #include <gsl/gsl_math.h>
24 #include <gsl/gsl_integration.h>
25
26 static double rescale_error (double err, const double result_abs, const double result_asc) ;
27
28 static double
rescale_error(double err,const double result_abs,const double result_asc)29 rescale_error (double err, const double result_abs, const double result_asc)
30 {
31 err = fabs(err) ;
32
33 if (result_asc != 0 && err != 0)
34 {
35 double scale = pow((200 * err / result_asc), 1.5) ;
36
37 if (scale < 1)
38 {
39 err = result_asc * scale ;
40 }
41 else
42 {
43 err = result_asc ;
44 }
45 }
46 if (result_abs > GSL_DBL_MIN / (50 * GSL_DBL_EPSILON))
47 {
48 double min_err = 50 * GSL_DBL_EPSILON * result_abs ;
49
50 if (min_err > err)
51 {
52 err = min_err ;
53 }
54 }
55
56 return err ;
57 }
58
59