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Re: Motion 31: V04.2 Revision of proposed Level 1 text



> Date: Thu, 1 Mar 2012 17:01:07 +0100
> From: Vincent Lefevre <vincent@xxxxxxxxxx>
> To: stds-1788 <stds-1788@xxxxxxxxxxxxxxxxx>
> Subject: Re: Motion 31: V04.2 Revision of proposed Level 1 text
> 
> On 2012-02-29 16:37:10 +0100, Ulrich Kulisch wrote:
> > Vincent:
> > 
> > Dan Zuras wrote on Febr. 13, 2012:
> > 
> > >I think that P1788 should not do the job of 754...
> > . . .
> > 
> > 
> > 	In principle, I agree with whoever said 1788 should
> > 	not do 754 things again.  And, indeed, you will find
> > 	the dot products&  related reductions as optional in
> > 	clause 9.4 of 754-2008.
> > 
> > 	Alas, we could not agree on making them mandatory&
> > 	we could not agree on an accuracy policy.
> > 
> > 	So if 1788 made them both mandatory&  exact (as Ulrich
> > 	wishes) it would not be repeating anything from 754.
> 
> Well, until Draft 04.3, P1788 Level 1 conflicted with IEEE 754
> (even if the specs are different, there should not be two dot
> products defined by two different standards -- it would be bad
> if each standard defined its own floating-point dot product).

	I was refering to the definition of the dot product,
	not any particular style of implementation such as
	complete arithmetic.

	And I think if we were to make it both mandatory &
	exact we would not find ourselves in conflict with
	754 (which has it as both optional & of unspecified
	quality).  We would merely be exercising that
	particular 754 option for 1788 conforming systems.

> 
> > The exact dot product could just be called 'edot'. It will
> > implicitely be introduced with complete arithmetic.
> 
> However complete arithmetic is something new. I see that the Level 1
> Draft 04.4 made things clear (referring to complete arithmetic, which
> was not the case before). So, currently this is fine.
> 
> Regards,
> 
> -- 
> Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>


	Oh, I think we can define an accurate dot product at
	level 1 without reference to complete arithmetic.

	More to the point I think we should.

	Complete arithmetic or any other methods of
	implementation just don't belong there.

	IMHO, as always...


				Dan