1 /* log1p(x) = log(1+x). The log1p function is designed to avoid the
2 significant loss of precision that arises from direct evaluation when x is
3 small. Use the substitute from _math.h on all platforms: it includes
4 workarounds for buggy handling of zeros.
5 */
6
7 static double
_Py_log1p(double x)8 _Py_log1p(double x)
9 {
10 /* Some platforms (e.g. MacOS X 10.8, see gh-59682) supply a log1p function
11 but don't respect the sign of zero: log1p(-0.0) gives 0.0 instead of
12 the correct result of -0.0.
13
14 To save fiddling with configure tests and platform checks, we handle the
15 special case of zero input directly on all platforms.
16 */
17 if (x == 0.0) {
18 return x;
19 }
20 else {
21 return log1p(x);
22 }
23 }
24
25 #define m_log1p _Py_log1p
26