File: _math.h

package info (click to toggle)
python3.13 3.13.6-1
  • links: PTS, VCS
  • area: main
  • in suites: sid
  • size: 121,256 kB
  • sloc: python: 703,743; ansic: 653,888; xml: 31,250; sh: 5,844; cpp: 4,326; makefile: 1,981; objc: 787; lisp: 502; javascript: 213; asm: 75; csh: 12
file content (25 lines) | stat: -rw-r--r-- 760 bytes parent folder | download | duplicates (3)
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
/* log1p(x) = log(1+x).  The log1p function is designed to avoid the
   significant loss of precision that arises from direct evaluation when x is
   small. Use the substitute from _math.h on all platforms: it includes
   workarounds for buggy handling of zeros.
 */

static double
_Py_log1p(double x)
{
    /* Some platforms (e.g. MacOS X 10.8, see gh-59682) supply a log1p function
       but don't respect the sign of zero:  log1p(-0.0) gives 0.0 instead of
       the correct result of -0.0.

       To save fiddling with configure tests and platform checks, we handle the
       special case of zero input directly on all platforms.
    */
    if (x == 0.0) {
        return x;
    }
    else {
        return log1p(x);
    }
}

#define m_log1p _Py_log1p