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 supply a log1p function but don't respect the sign of
11        zero:  log1p(-0.0) gives 0.0 instead of the correct result of -0.0.
12 
13        To save fiddling with configure tests and platform checks, we handle the
14        special case of zero input directly on all platforms.
15     */
16     if (x == 0.0) {
17         return x;
18     }
19     else {
20         return log1p(x);
21     }
22 }
23 
24 #define m_log1p _Py_log1p
25