Re: Detect negative zero (was Re: Infinity as index)

[Doug Currie <doug.currie@...>]

On 24/04/14 17:15, Dirk Laurie wrote:
>
> The hardest test of all is to distinguish between 0 and -0.
> If you can improve on the following, please post.
>
> if x==0 and 1/x>0 then -- x is 0
> if x==0 and 1/x<0 then -- x is -0

You can get by without the and:

> function is_minuszero (x) return 1/x == -1/0 end

> function is_pluszero (x) return 1/x == 1/0 end 

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