Branch data     Line data    Source code

       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
       8                 :        370 : _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         [ +  + ]:        370 :     if (x == 0.0) {
      17                 :         82 :         return x;
      18                 :            :     }
      19                 :            :     else {
      20                 :        288 :         return log1p(x);
      21                 :            :     }
      22                 :            : }
      23                 :            : 
      24                 :            : #define m_log1p _Py_log1p