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/* 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 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
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