[Cfp-interest 1800] Re: Exact subnormal results

[Damian McGuckin]

Hi Jim,

On Tue, 20 Oct 2020, Jim Thomas wrote:

> The definitions are in 7.12.1 in
> http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2573.pdf
> 
> I assume you?re asking about the C standard.

Because if you look there, the word underflow is used long before it 
appears in any definition.

On page 450,

 	The "underflow" floating-point exception is raised whenever a
 	result is tiny (essentially subnormal or zero) and suffers loss of
 	accuracy.

Given:

 	0.25 * 2**emin

does this overflow. Because it is exact.  But is Page 450 the strict 
definition. Because, that answers Fred's question (and agrees with Fred).

I actually meant in the latest IEEE 754 (or IEC).

Sorry, if I seem rushed. I am off to two meetings and did not have time to 
look it up as thoroughly as I would have liked. But I wanted to get the 
email out before your part of the world went to bed.

Regards - Damian

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