[Python-checkins] r62400 - python/trunk/Modules/mathmodule.c
mark.dickinson
python-checkins at python.org
Sat Apr 19 21:41:52 CEST 2008
Author: mark.dickinson
Date: Sat Apr 19 21:41:52 2008
New Revision: 62400
Log:
Additional special-case handling for math.pow.
Windows/VS2008 doesn't like (-1)**(+-inf).
Modified:
python/trunk/Modules/mathmodule.c
Modified: python/trunk/Modules/mathmodule.c
==============================================================================
--- python/trunk/Modules/mathmodule.c (original)
+++ python/trunk/Modules/mathmodule.c Sat Apr 19 21:41:52 2008
@@ -521,9 +521,19 @@
y = PyFloat_AsDouble(oy);
if ((x == -1.0 || y == -1.0) && PyErr_Occurred())
return NULL;
- /* 1**x and x**0 return 1., even if x is a NaN or infinity. */
- if (x == 1.0 || y == 0.0)
+
+ /* deal directly with various special cases, to cope with problems on
+ various platforms whose semantics don't exactly match C99 */
+
+ /* 1**x, x**0, and (-1)**(+-infinity) return 1., even if x is NaN or
+ an infinity. */
+ if (x == 1. || y == 0. || (x == -1. && Py_IS_INFINITY(y)))
return PyFloat_FromDouble(1.);
+ /* otherwise, return a NaN if either input was a NaN */
+ if (Py_IS_NAN(x))
+ return PyFloat_FromDouble(x);
+ if (Py_IS_NAN(y))
+ return PyFloat_FromDouble(y);
/* 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;
@@ -539,10 +549,7 @@
r = pow(x, y);
PyFPE_END_PROTECT(r);
if (Py_IS_NAN(r)) {
- if (!Py_IS_NAN(x) && !Py_IS_NAN(y))
- errno = EDOM;
- else
- errno = 0;
+ errno = EDOM;
}
/* an infinite result arises either from:
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