On Mon, Mar 12, 2018, 3:25 PM Tim Peters <tim.pet...@gmail.com> wrote:
> [David Mertz <me...@gnosis.cx>]
> > ...
> > I can see no sane reason why anyone would ever call float.is_integer()
> > actually. That should always be spelled math.isclose(x, int(x)) because
> > IEEE-754. Attractive nuisance is probably too generous, I'd simply call
> > method a bug.
> Sometimes it's necessary to know, and especially when _implementing_
> 754-conforming functions. For example, what negative infinity raised
> to a power needs to return depends on whether the power is an integer
> (specifically on whether it's an odd integer):
> >>> (-math.inf) ** 3.1
Weird. I take it that's what IEEE-754 says. NaN would sure be more
intuitive here since inf+inf-j is not in the domain of Reals. Well,
technically neither is inf, but at least it's the limit of the domain. :-).
>>> (-math.inf) ** 3.0 # NOTE THIS ONE
> >>> (-math.inf) ** 2.9
> But, ya, for most people most of the time I agree is_integer() is an
> attractive nuisance. People implementing math functions are famous
> for cheerfully enduring any amount of pain needed to get the job done
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