SF bug 533198: Complex power underflow raises exception.
Konrad was too kind. Not only did it raise an exception, the specific
exception it raised made no sense. These are old bugs in complex_pow()
and friends:
1. Raising 0 to a negative power isn't a range error, it's a domain
error, so changed c_pow() to set errno to EDOM in that case instead
of ERANGE.
2. Changed complex_pow() to:
A. Used the Py_ADJUST_ERANGE2 macro to try to clear errno of a spurious
ERANGE error due to underflow in the libm pow() called by c_pow().
B. Produced different exceptions depending on the errno value:
i) For errno==EDOM, raise ZeroDivisionError instead of ValueError.
This is for consistency with the non-complex cases 0.0**-2 and
0**-2 and 0L**-2.
ii) For errno==ERANGE, raise OverflowError.
Bugfix candidate.
diff --git a/Objects/complexobject.c b/Objects/complexobject.c
index 0bc388b..48a9afa 100644
--- a/Objects/complexobject.c
+++ b/Objects/complexobject.c
@@ -131,7 +131,7 @@
}
else if (a.real == 0. && a.imag == 0.) {
if (b.imag != 0. || b.real < 0.)
- errno = ERANGE;
+ errno = EDOM;
r.real = 0.;
r.imag = 0.;
}
@@ -456,11 +456,17 @@
p = c_pow(v->cval,exponent);
PyFPE_END_PROTECT(p)
- if (errno == ERANGE) {
- PyErr_SetString(PyExc_ValueError,
+ Py_ADJUST_ERANGE2(p.real, p.imag);
+ if (errno == EDOM) {
+ PyErr_SetString(PyExc_ZeroDivisionError,
"0.0 to a negative or complex power");
return NULL;
}
+ else if (errno == ERANGE) {
+ PyErr_SetString(PyExc_OverflowError,
+ "complex exponentiaion");
+ return NULL;
+ }
return PyComplex_FromCComplex(p);
}