Re: A motion 33 query
On 2012-05-22 18:15:33 +0100, John Pryce wrote:
> Vincent
>
> The discussion on Motion 33, includes an exchange between Dmitry and
> yourself, see below. I also had thought the motion text doesn't make
> it clear enough that (B1)-(B4) are not about what an IEEE number
> format *is*, but about how it binds to P1788, or rather to
> (A1)-(A5).
Well, what the motion says is that a number format as specified
by IEEE 754 is regarded as a 754 number format by P1788 only if
(B1)-(B4) are satisfied. For instance, this is not said explicitly,
but for B3, it is quite clear than the +0 (resp. -0) of the
IEEE 754 format must correspond to the +0 (resp. -0) of the
P1788 number format. If the sign of 0 is ignored[*] in the P1788
implementation (or if the meanings of the signs are exchanged
between IEEE 754 and the P1788 implementation), then it is not
a 754 format for P1788.
[*] i.e. does not conform to one of the possible future requirements
on the sign of zero (such requirements will be discussed in future
motions, with the definition of the functions).
> You said Dmitry's proposed emendation to the wording, "The notion
> ... binding to (A1)-(A5)" is a good one. Should we take it that the
> motion now includes these words? The version currently on the P1788
> Motions web page doesn't include them.
Yes, I thought it was on the web page. I suggested the change
privately:
------------------------------------------------------------------------
Date: Tue, 22 May 2012 16:18:23 +0200
From: Vincent Lefevre <vincent@xxxxxxxxxx>
To: "J. Wolff von Gudenberg" <wolff@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: motion number format
On 2012-05-22 15:54:44 +0200, J. Wolff von Gudenberg wrote:
> Vincent
> please check if I published the correct version of your motion
> Juergen
Dmitry suggested another change:
The notion of a 754-conforming implementation has been introduced
in Motion 6.04. A 754 format must have the following additional
requirements:
to:
The notion of a 754-conforming implementation has been introduced
in Motion 6.04. A 754 format is one of the number formats defined
in IEEE 754 with the following binding to A1-A5:
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Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)