| /* sys/ldfrexp.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. |
| */ |
| |
| #include <config.h> |
| #include <math.h> |
| #include <gsl/gsl_math.h> |
| |
| double |
| gsl_ldexp (const double x, const int e) |
| { |
| double p2 = pow (2.0, (double)e); |
| return x * p2; |
| } |
| |
| double |
| gsl_frexp (const double x, int *e) |
| { |
| if (x == 0.0) |
| { |
| *e = 0; |
| return 0.0; |
| } |
| else |
| { |
| double ex = ceil (log (fabs (x)) / M_LN2); |
| int ei = (int) ex; |
| double f = gsl_ldexp (x, -ei); |
| |
| while (fabs (f) >= 1.0) |
| { |
| ei++; |
| f /= 2.0; |
| } |
| |
| while (fabs (f) < 0.5) |
| { |
| ei--; |
| f *= 2.0; |
| } |
| |
| *e = ei; |
| return f; |
| } |
| } |