From bab22beda8583471caf44b2e91f0fc18b62d3405 Mon Sep 17 00:00:00 2001 From: Tim Peters Date: Fri, 22 Mar 2002 02:48:46 +0000 Subject: [PATCH] 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. --- Objects/complexobject.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/Objects/complexobject.c b/Objects/complexobject.c index 0bc388b896b..48a9afa2e7f 100644 --- a/Objects/complexobject.c +++ b/Objects/complexobject.c @@ -131,7 +131,7 @@ c_pow(Py_complex a, Py_complex b) } 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 @@ complex_pow(PyComplexObject *v, PyObject *w, PyComplexObject *z) 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); }