3 * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
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.
20 /* Author: G. Jungman */
23 #include <gsl/gsl_math.h>
24 #include <gsl/gsl_errno.h>
25 #include <gsl/gsl_sf_pow_int.h>
28 /*-*-*-*-*-*-*-*-*-*-*-* Functions w/ Error handling *-*-*-*-*-*-*-*-*-*-*-*/
30 int gsl_sf_pow_int_e(double x, int n, gsl_sf_result * result)
35 /* CHECK_POINTER(result) */
43 result->val = (n % 2) ? u : (u * u) ; /* correct sign of infinity */
44 result->err = GSL_POSINF;
45 GSL_ERROR ("overflow", GSL_EOVRFLW);
51 /* repeated squaring method
52 * returns 0.0^0 = 1.0, so continuous in x
55 if(GSL_IS_ODD(n)) value *= x;
62 result->err = 2.0 * GSL_DBL_EPSILON * (count + 1.0) * fabs(value);
67 /*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
71 double gsl_sf_pow_int(const double x, const int n)
73 EVAL_RESULT(gsl_sf_pow_int_e(x, n, &result));