From owner-sc22wg5@dkuug.dk Fri Aug 15 03:23:28 2003 Received: (from majordom@localhost) by dkuug.dk (8.12.8p1/8.9.2) id h7F1NS0I075969 for sc22wg5-domo; Fri, 15 Aug 2003 03:23:28 +0200 (CEST) (envelope-from owner-sc22wg5@dkuug.dk) X-Authentication-Warning: ptah.dkuug.dk: majordom set sender to owner-sc22wg5@dkuug.dk using -f Received: from nwkea-mail-1.sun.com (nwkea-mail-1.sun.com [192.18.42.13]) by dkuug.dk (8.12.8p1/8.9.2) with ESMTP id h7F1NLEc075963 for ; Fri, 15 Aug 2003 03:23:25 +0200 (CEST) (envelope-from corbett@mpkmail.eng.sun.com) Received: from engmail2sun.Eng.Sun.COM ([129.144.134.19]) by nwkea-mail-1.sun.com (8.12.9/8.12.9) with ESMTP id h7F1NEjL018781; Thu, 14 Aug 2003 18:23:15 -0700 (PDT) Received: from phys-mpkmaila (phys-mpkmaila.SFBay.Sun.COM [129.146.18.131]) by engmail2sun.Eng.Sun.COM (8.12.9+Sun/8.12.9/ENSMAIL,v2.2) with ESMTP id h7F1NEUu017077; Thu, 14 Aug 2003 18:23:14 -0700 (PDT) Received: from lupa (lupa.Eng.Sun.COM [129.146.78.104]) by mpkmail.eng.sun.com (iPlanet Messaging Server 5.2 Patch 1 (built Apr 2 2002)) with SMTP id <0HJM003QOZUQXJ@mpkmail.eng.sun.com>; Thu, 14 Aug 2003 18:23:14 -0700 (PDT) Date: Thu, 14 Aug 2003 18:23:14 -0700 (PDT) From: Robert Corbett Subject: Re: (SC22WG5.2936) clarification of technical intent in N1553 To: sc22wg5@dkuug.dk, malcolm@nag.co.uk Reply-to: Robert Corbett Message-id: <0HJM003QPZUQXJ@mpkmail.eng.sun.com> MIME-version: 1.0 X-Mailer: dtmail 1.3.0 @(#)CDE Version 1.4.8 SunOS 5.8 sun4u sparc Content-type: TEXT/plain; charset=us-ascii Content-transfer-encoding: 7BIT Content-MD5: x1SUG7IrtCRReTBEwcBmPw== Sender: owner-sc22wg5@dkuug.dk Precedence: bulk > Robert Corbett wrote: > > Does it not bother the Fortran committees that they are > > approving a different syntax for reading and writing > > formatted NaN values from the syntax proposed by the > > IEEE floating-point committee? > > No, because there is no such syntax. > > At the time of the last meeting, the proposal for formatting NaN values > in strings had the status of "not discussed by the IEEE committee", i.e. > someone had sent it in but it had not even been discussed, let alone > decided upon. If you read the change log in the proposal, you will find that the proposal has been considered by the committee. The part about reading and writing NaNs was proposed in November and agreed on Feb. 12. > As Aleksandar noted, in any case we cannot wait for the 754r committee > to finish. I'll further note that the 754r committee is seriously > considering (to the extent that it was a declared intention!) NOT to > be upwardly compatible with 754. Whether the extent of the differences > will be easily papered over by software alterations, or whether this > means new hardware, is unclear. > > >I am not certain you have not, since I have not seen the latest > >version of your proposed syntax. However, based on the e-mail > >I have seen, it does not appear you have. > > Actually, some of us had seen it. I am not surprised that some members of WG5 have seen the Fortran proposal. > > The IEEE proposal uses > >the sequence "sNaN" to indicate a signaling NaN. It used an > >optional `+' and a mandatory `-' to indicate the sign of the NaN. > > IMO such characteristics are completely broken (not to mention > internally contradictory - both 754 and all drafts of 754r say > that they do NOT interpret the signs of NaNs!). > > And certainly 754 has licence for signalling NaNs to become nonsignalling > at the drop of a hat (even on a "copy" operation), so making that > characteristic the most important one (by putting it first) would be > inappropriate. The sign comes first. > >I don't think either of those parts of the IEEE proposal are > >part of the syntax the draft Fortran standard is using. > > Absolutely! I suggest that the committee add a note to the rationale saying that they were aware of the proposed IEEE syntax for reading and writing NaNs and chose a different syntax. That might prevent problems for implementors later. Sincerely, Bob Corbett