| 1 | /* Logarithm. |
| 2 | Copyright (C) 2012-2014 Free Software Foundation, Inc. |
| 3 | |
| 4 | This program is free software: you can redistribute it and/or modify |
| 5 | it under the terms of the GNU Lesser General Public License as published by |
| 6 | the Free Software Foundation; either version 3 of the License, or |
| 7 | (at your option) any later version. |
| 8 | |
| 9 | This program is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | GNU Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public License |
| 15 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 16 | |
| 17 | #include <config.h> |
| 18 | |
| 19 | /* Specification. */ |
| 20 | #include <math.h> |
| 21 | |
| 22 | double |
| 23 | log (double x) |
| 24 | #undef log |
| 25 | { |
| 26 | if (x <= 0.0) |
| 27 | { |
| 28 | /* Work around the OSF/1 5.1 bug. */ |
| 29 | if (x == 0.0) |
| 30 | /* Return -Infinity. */ |
| 31 | return -1.0 / 0.0; |
| 32 | /* Work around the NetBSD 5.1, Solaris 11 2011-11 bug. */ |
| 33 | else /* x < 0.0 */ |
| 34 | /* Return NaN. */ |
| 35 | return 0.0 / 0.0; |
| 36 | } |
| 37 | return log (x); |
| 38 | } |