Re: RFA: don't try to compare IEEE NaN's

[Michael Snyder <msnyder at cygnus dot com>]

Eli Zaretskii wrote:
> 
> On 6 Jun 2001, Jim Blandy wrote:
> 
> > What you're saying is that, between this:
> >
> >         union {
> >           float f;
> >           char bytes[80];
> >         } u;
> >
> >         for (i = 0; i < 80; i++)
> >           u.bytes[i] = something interesting;
> >
> > and this:
> >
> >         u.f = 2.7182818284590452354;
> >
> > that you're more concerned that the latter will put a NaN in u.f than
> > the former.
> 
> Yes.
> 
> > When, in fact, the exact problem I'm trying to fix is
> > that someone's first shot at the former strategy produced a NaN.
> 
> That's because the bit pattern used by the original code was a bit
> pattern of a NaN in the first place.  In other words, we've got
> exactly what we were asking for.  You cannot expect that with a
> literal FP constant like the one you used.

I was not specifically trying to create a NaN -- 
just a recognizeable bit pattern.

Michael