1 /* Natural logarithmic function. 2 Copyright (C) 2011-2021 Free Software Foundation, Inc. 3 4 This file is free software: you can redistribute it and/or modify 5 it under the terms of the GNU Lesser General Public License as 6 published by the Free Software Foundation; either version 3 of the 7 License, or (at your option) any later version. 8 9 This file 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 <https://www.gnu.org/licenses/>. */ 16 17 #include <config.h> 18 19 /* Specification. */ 20 #include <math.h> 21 22 float 23 logf (float x) /* */ 24 #undef logf 25 { 26 #if HAVE_LOGF 27 if (x <= 0.0f) 28 { 29 /* Work around the OSF/1 5.1 bug. */ 30 if (x == 0.0f) 31 /* Return -Infinity. */ 32 return -1.0f / 0.0f; 33 /* Work around the NetBSD 5.1 bug. */ 34 else /* x < 0.0 */ 35 /* Return NaN. */ 36 return 0.0f / 0.0f; 37 } 38 return logf (x); 39 #else 40 return (float) log ((double) x); 41 #endif 42 }