Re: Building current...

[Paul Koning <paulkoning%comcast.net@localhost>]

> On Dec 4, 2015, at 12:16 PM, Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:
> 
>> Given this discussion, I'm inclined to view the existence of Inf and NaN a d$
> 
> (Please don't use paragraph-length lines.)

I'll try.  Not clear how to get Mac mail to do that.

> I'm not so sure.  Infinities, maybe.  NaNs, I don't think so, though an
> argument could be made that quiet NaNs are.
> 
> Unless you come up with a meaning for every bit pattern, you will have
> some kind of erroneous patterns to deal with.  The VAX calls them
> reserved operands.  IEEE split them up, leaving some as more or less
> the same thing - calling them signaling NaNs - and splitting some off
> into quiet NaNs and infinities as well.  (They also, as compared to the
> VAX, created denormalized numbers, but I've seen no reason to think
> they are any more problematic than any of the other ways of dealing
> with exponent underflow.)  The mistakes (if that's what they are - I'm
> not entirely convinced), were quiet NaNs and infinities.

Yes, you're right.  A signaling NaN is fine.  What I object to is
mechanisms that take a bug (a mathematically invalid operation)
and silently turn it into a "valid" answer.

Denorms are a different topic.  That's a way to make the range of
the numbers slighty larger at the small end, at the expense of losing
one bit of precision in all other cases.

	paul