[cfp-interest 3621] Re: Rounding Mode

[Damian McGuckin]

On Tue, 23 Sep 2025, Jim Thomas wrote:

> Rounding precision mode is in 754-1985, but not in later versions. The 
> attention to rounding precision mode was added to C99 which was designed 
> to support 754-1985. Since 754 no longer mentions rounding precision 
> mode (and assuming the current revision is unlikely to restore it as a 
> feature), why should we elevate its status in C2Y? Just mentioning it as 
> a possible extension, as in footnote 438 in F.8.1, seems appropriate.

Agreed.
>
> F.8.3 and F.8.4 incorrectly imply that rounding precision mode is an 
> optional feature of ISO/IEC 60559. (Likewise, ?trapping? is no longer 
> mentioned as a user feature in 754. Traps are mentioned only in an 
> implementation note.) We might consider updating F.8.3. and F.8.4 to 
> remove the reference to rounding precision (and trapping) mode which is 
> obsolete from a standards perspective.

Your call.

> Choosing terms specifically to accommodate rounding precision mode 
> doesn?t seem needed.

Sorry. I was not suggesting that. I was unclear.  Silly me.

The two terms

 	rounding direction mode
and
 	rounding mode

are used interchangably throughout the standard for exactly the same thing 
and I am arging that they be made consistent. From what David said, as the 
IEEE 754 equivalent term is

 	rounding direction attribute

it would seem like the former is best?  What do you recommend of the two?

Thanks - Damian