index 08ebbf4678ea55ef70d0726082506f15c95b52ad..086631dd19ff4e345c44b8925e7184cb12569f54 100644 (file)
if (arg2 == floor(arg2))
{
/* y is integral; it's odd if y/2 is not integral */
- double halfy = arg2 * 0.5; /* should be computed exactly */
+ double halfy = arg2 / 2; /* should be computed exactly */
if (halfy != floor(halfy))
yisoddinteger = true;
if (errno == EDOM || isnan(result))
{
/*
- * We eliminated all the possible domain errors above, or should
- * have; but if pow() has a more restrictive test for "is y an
- * integer?" than we do, we could get here anyway. Historical
- * evidence suggests that some platforms once implemented the test
- * as "y == (long) y", which of course misbehaves beyond LONG_MAX.
- * There's not a lot of choice except to accept the platform's
- * conclusion that we have a domain error.
+ * We handled all possible domain errors above, so this should be
+ * impossible. However, old glibc versions on x86 have a bug that
+ * causes them to fail this way for abs(y) greater than 2^63:
+ *
+ * https://sourceware.org/bugzilla/show_bug.cgi?id=3866
+ *
+ * Hence, if we get here, assume y is finite but large (large
+ * enough to be certainly even). The result should be 0 if x == 0,
+ * 1.0 if abs(x) == 1.0, otherwise an overflow or underflow error.
*/
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
- errmsg("a negative number raised to a non-integer power yields a complex result")));
+ if (arg1 == 0.0)
+ result = 0.0; /* we already verified y is positive */
+ else
+ {
+ double absx = fabs(arg1);
+
+ if (absx == 1.0)
+ result = 1.0;
+ else if (arg2 >= 0.0 ? (absx > 1.0) : (absx < 1.0))
+ float_overflow_error();
+ else
+ float_underflow_error();
+ }
}
else if (errno == ERANGE)
{