[Haskell-cafe] Re: 0/0 > 1 == False
Achim Schneider
barsoap at web.de
Fri Jan 11 08:54:20 EST 2008
Ketil Malde <ketil+haskell at ii.uib.no> wrote:
> Achim Schneider <barsoap at web.de> writes:
>
> >> You need to use the / operator, if you want to do floating-point
> >> division.
>
> > Yes, exactly, integers don't have +-0 and +-infinity... only
> > (obviously) a kind of nan.
>
> No, failure (exception, bottom) is different from NaN, which is just
> another value in the domain - admittedly one which behaves rather
> strangely.
>
s/a kind of/not entirely unlike a/
> > Said differently: I don't know a thing about floats or numerics.
>
> Perhaps it helps to think of floating point values as intervals? If +0
> means some number between 0 and the next possible representable
> number (and similar for -0), it may make more sense to have 1/+0 and
> 1/-0 behave differently.
>
Hmmm... ah.
+-0 / +-0 is always NaN 'cos you can't tell which one is bigger and
thus can't decide between positive and negative Infinity, and it
isn't both, either.
But then there's +0/0 and -0/0, which would be +Infinity and
-Infinity, and +0 > 0 > -0. AFAIK there are no floats with three zero
values, though.
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