1 /* Base 10 logarithmic function. 2 Copyright (C) 2012-2021 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 #if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE 23 24 long double 25 log10l (long double x) /* */ 26 { 27 return log10 (x); 28 } 29 30 #elif 0 /* was: HAVE_LOG10L */ 31 32 # include <float.h> 33 34 long double 35 log10l (long double x) /* */ 36 # undef log10l 37 { 38 /* Work around the OSF/1 5.1 bug. */ 39 if (x == 0.0L) 40 /* Return -Infinity. */ 41 return -1.0L / 0.0L; 42 { 43 long double y = log10l (x); 44 # ifdef __sgi 45 /* Normalize the +Infinity value. */ 46 if (y > LDBL_MAX) 47 y = 1.0L / 0.0L; 48 # endif 49 return y; 50 } 51 } 52 53 #else 54 55 /* 1 / log(10) */ 56 static const long double inv_log10 = 57 0.43429448190325182765112891891660508229439700580366656611445378316586464920887L; 58 59 long double 60 log10l (long double x) /* */ 61 { 62 return logl (x) * inv_log10; 63 } 64 65 #endif