Re: DirectedInf
> Date: Tue, 05 Oct 2010 19:58:12 +0200
> From: Arnold Neumaier <Arnold.Neumaier@xxxxxxxxxxxx>
> To: Nate Hayes <nh@xxxxxxxxxxxxxxxxx>
> CC: 1788 <stds-1788@xxxxxxxxxxxxxxxxx>
> Subject: DirectedInf
>
> Nate Hayes wrote: [in Overflow and Inf]
> > Arnold Neumaier wrote:
> >> Nate Hayes wrote:
> >>> Arnolde Neumaier wrote:
> >>>>
> >>>> I assume you refer to Ian Mcintosh's mail from September 22.
> >>>> What he says is independent of whether a distinction is made between
> >>>> Inf and Overflow.
> >>>>
> >>>> It applies verbatim if all of his Overflows are interpreted as Inf
> >>>> in the sense of Motion 3, but are implemented as nonstandard Inf
> >>>> (called DirectedInf for the sake of the following discussion)
> >>>> for which an implementation can (apparently, if I understand
> >>>> him correctly) specify its own operation rules without being
> >>>> inconsistent with 754.
>
> Since Dan Zuras and Michel Hack assure me that adding new rounding modes
> does not invalidate the property of being 754-conforming, the above
> seems indeed to be the case, interpreted appropriately.
>
> This opens up a door that I'll soon expl;ore in more detail.
>
Arnold,
You seem to be picking & choosing from among my words
to support your approach.
I do NOT support it. And I believe it WOULD invalidate
a system from conforming to 754.
I repeat the next paragraph from that note:
>>
>> However, if you are asking that there exist values
>> (such as +/-DirectedInf) other than those spelled out
>> in the 754 document, I'd have to say, yes, that would
>> invalidate an implementation.
>>
>> The clause you would violate is section 3.3 & I quote:
>>
>> "These are the only floating-point data represented."
>>
I believe this WOULD violate both the letter & the
spirit of IEEE-754.
Something that I went on to opine would be unwise of
us to do.
I am NOT opening that door for you. You force yourself
through it by yourself.
Dan