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gh-122681: merge m_atan2() and c_atan2() helper functions (#122682)

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Sergey B Kirpichev 2024-08-06 15:43:13 +03:00 • committed by GitHub
parent 6ff82fdb56
commit 0b433aa9df
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3 changed files with 41 additions and 69 deletions
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39
Modules/_math.h
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@ -23,3 +23,42 @@ _Py_log1p(double x)
}
#define m_log1p _Py_log1p
/*
wrapper for atan2 that deals directly with special cases before
delegating to the platform libm for the remaining cases. This
is necessary to get consistent behaviour across platforms.
Windows, FreeBSD and alpha Tru64 are amongst platforms that don't
always follow C99. Windows screws up atan2 for inf and nan, and
alpha Tru64 5.1 doesn't follow C99 for atan2(0., 0.).
*/
static double
_Py_atan2(double y, double x)
{
if (isnan(x) || isnan(y))
return Py_NAN;
if (isinf(y)) {
if (isinf(x)) {
if (copysign(1., x) == 1.)
/* atan2(+-inf, +inf) == +-pi/4 */
return copysign(0.25*Py_MATH_PI, y);
else
/* atan2(+-inf, -inf) == +-pi*3/4 */
return copysign(0.75*Py_MATH_PI, y);
}
/* atan2(+-inf, x) == +-pi/2 for finite x */
return copysign(0.5*Py_MATH_PI, y);
}
if (isinf(x) || y == 0.) {
if (copysign(1., x) == 1.)
/* atan2(+-y, +inf) = atan2(+-0, +x) = +-0. */
return copysign(0., y);
else
/* atan2(+-y, -inf) = atan2(+-0., -x) = +-pi. */
return copysign(Py_MATH_PI, y);
}
return atan2(y, x);
}
#define m_atan2 _Py_atan2