lib/log.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

/* Logarithm.
   Copyright (C) 2012-2019 Free Software Foundation, Inc.

   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 3 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, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include <math.h>

double
log (double x)
#undef log
{
  if (x <= 0.0)
    {
      /* Work around the OSF/1 5.1 bug.  */
      if (x == 0.0)
        /* Return -Infinity.  */
        return -1.0 / 0.0;
      /* Work around the NetBSD 5.1, Solaris 11.0 bug.  */
      else /* x < 0.0 */
        /* Return NaN.  */
        return 0.0 / 0.0;
    }
  return log (x);
}