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On Friday 25 July 2008 04:14:22 pm Matthew William Cox wrote:
> On Thu, Jul 24, 2008 at 09:40:36PM -0400, Peng Zang wrote:
> > Yeah, that always seemed broken to me.  If two things are physically
> > equal (they occupy the same memory space) it doesn't make sense for them
> > to be structurally unequal (contain different content).  Personally, one
> > of the first things I did is redefined (=) to fix this.
>
> It's not broken at all, but complient with a common and longstanding
> idiom (at least amoung scientists working with numerical codes.) The way
> we test for NaN is by comparing to itself, eg:
>
>     if x = x then (* x is a number *) else (* x is NaN *)
>
> Matt

Yeah, I just learned that today.  But these days, most languages have 
functions for testing for NaN.  OCaml has classify_float for example.  Just 
FYI

Peng
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