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25 lines
760 B
C
25 lines
760 B
C
/* log1p(x) = log(1+x). The log1p function is designed to avoid the
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significant loss of precision that arises from direct evaluation when x is
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small. Use the substitute from _math.h on all platforms: it includes
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workarounds for buggy handling of zeros.
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*/
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static double
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_Py_log1p(double x)
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{
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/* Some platforms (e.g. MacOS X 10.8, see gh-59682) supply a log1p function
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but don't respect the sign of zero: log1p(-0.0) gives 0.0 instead of
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the correct result of -0.0.
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To save fiddling with configure tests and platform checks, we handle the
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special case of zero input directly on all platforms.
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*/
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if (x == 0.0) {
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return x;
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}
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else {
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return log1p(x);
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}
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}
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#define m_log1p _Py_log1p
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