Mercurial > cpython-lru_cache-weakref
diff Modules/mathmodule.c @ 46486:82d85a05923b legacy-trunk
Additional tests for math.pow, and extra special-case
handling code in math.pow, in the hope of making all
tests pass on the alpha Tru64 buildbot.
| author | Mark Dickinson <dickinsm@gmail.com> |
|---|---|
| date | Sat, 19 Apr 2008 18:51:48 +0000 |
| parents | 5bc7b20dc04a |
| children | 648b4d01cccf |
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--- a/Modules/mathmodule.c Sat Apr 19 17:00:14 2008 +0000 +++ b/Modules/mathmodule.c Sat Apr 19 18:51:48 2008 +0000 @@ -513,6 +513,7 @@ { PyObject *ox, *oy; double r, x, y; + int y_is_odd; if (! PyArg_UnpackTuple(args, "pow", 2, 2, &ox, &oy)) return NULL; @@ -523,6 +524,16 @@ /* 1**x and x**0 return 1., even if x is a NaN or infinity. */ if (x == 1.0 || y == 0.0) return PyFloat_FromDouble(1.); + /* inf ** (nonzero, non-NaN) is one of +-0, +-infinity */ + if (Py_IS_INFINITY(x) && !Py_IS_NAN(y)) { + y_is_odd = Py_IS_FINITE(y) && fmod(fabs(y), 2.0) == 1.0; + if (y > 0.) + r = y_is_odd ? x : fabs(x); + else + r = y_is_odd ? copysign(0., x) : 0.; + return PyFloat_FromDouble(r); + } + errno = 0; PyFPE_START_PROTECT("in math_pow", return 0); r = pow(x, y);