On Wed, 17 Feb 2010 10:06:01 am Mark Dickinson wrote:
On Tue, Feb 16, 2010 at 10:46 PM, Steven D'Aprano <steve@pearwood.info>
What's the justification for that convention? It seems wrong to me.
It's difficult to do better than to point to Kahan's writings. See
http://www.eecs.berkeley.edu/~wkahan/ieee754status/IEEE754.PDF
Well, who am I to question Kahan? I guess if you interpret nan as "indeterminate", than hypot(inf, nan) should be inf; but if you interpret it as "not a number", then it should be nan. Since NANs can be both, I guess we're stuck with one or the other. So I'm satisfied that there's a good reason for the behaviour, even if I'm not 100% convinced it's the best reason. On a related note, why the distinction here?
inf*inf inf inf**2 Traceback (most recent call last): File "<stdin>", line 1, in <module> OverflowError: (34, 'Numerical result out of range')
-- Steven D'Aprano