Re: Math patch

[Chris Gray]

On Thu, 27 Feb 2003, Jeroen Frijters wrote:

> Hi,
> 
> Attached is a small patch to java.lang.Math to make round(float) and
> round(double) do the right thing for NaN.
> 
> Style wise, is it a good idea to use "a != a" to test for NaN, or should
> Double.isNaN() be used?

This is an old chestnut. ;) For some VMs, Double.isNaN() will translate to 
an (expensive) JNI method call. For others it's no big deal. So on the 
whole "a != a" seems like the better bet. Hm, I see Wonka's java.lang.Math 
contains 21 "a != a" constructs and 2 "Double.isNaN(a)"'s. :-/

What we really need is
#define isNaN(a) ((a) != (a))

;>

-- 

Chris Gray

VM Architect, ACUNIA