checking whether the number is NaN

Zhenya zheny at list.ru
Fri Dec 28 16:54:46 PST 2012


On Friday, 28 December 2012 at 20:19:49 UTC, Simen Kjaeraas wrote:
> On 2012-42-28 16:12, Zhenya <zheny at list.ru> wrote:
>
>> Hi!
>> Tell me please,are there any way to check whether number is 
>> NaN?
>
> us std.math.isNaN. But if you really don't want to:
>
> float x = ...;
>
> if (x != x) {
>     writeln( "x is NaN" );
> }
>
> I'm unsure how aggressive the optimizer is allowed to be in 
> cases
> like this. Theoretically it could assume x is always equal to x,
> but I'd think it's not allowed to for floats.
>
> If you're wondering how a float value could compare different to
> the exact same value, consider that this would otherwise be 
> true:
>
> sqrt(-1) == 0/0

Thank you,understood)
It's a nice way.


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