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)
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*/
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)
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*/
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)
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*/
61 {
62 return logl (x) * inv_log10;
63 }
64
65 #endif