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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 : 60 : _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 [ + + ]: 60 : if (x == 0.0) { 18 : 2 : return x; 19 : : } 20 : : else { 21 : 58 : return log1p(x); 22 : : } 23 : : } 24 : : 25 : : #define m_log1p _Py_log1p