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Re: C binding for IEEE 754-2008



From: Jim Thomas <jaswthomas@xxxxxxxxxxxxx>
Subject: C binding for IEEE 754-2008
Date: Mon, 16 Jul 2012 16:56:04 -0700
Cc: CFP <cfp-interest@xxxxxxxxxxx>, John Benito <benito@xxxxxxxxxxxxx>
To: stds-754@xxxxxxxx


A C floating point study group, under ISO/IEC JTC1/SC22/WG14, the =
international standardization working group for the programming language =
C, has been working on a C language binding for IEEE Std 754-2008. WG14 =
is currently seeking approval to adopt this specification as a work =
item. A draft of Part 1 of the specification is posted at =
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1615.pdf for early =
informal review. Your review and input would be much appreciated. Please =
send comments to the study group reflector at cfp-interest@xxxxxxxxxxx.

-Jim Thomas=

        Jim,

        (From just a few cursory readings.)

        I see almost no mention of either the newly defined
        tower of precisions or the elements of Clause 9 other
        than their mention WRT rounding modes.  Although it
        mentions that these will appear in parts 3 through 5.

        While I recognise that both the tower & transcendental
        functions are optional, not specifying them for C means
        that C (likely) never intendeds to support them.

        If this is so it should be stated up front.  Or, if it
        is intended that they be supported in some later
        revision of C, that should be stated.

        While it is mentioned (up front) that 754 went to a
        lot of trouble to support intelligent reproducibility,
        there seems to be less support of it within C.  Same
        comments as above.  (Or are these in part 5?)

        I notice that support of those things that will lead
        to the support of intervals is also not mentioned
        even though we went to some trouble to put them in
        754.  As there is a committee currently working on
        the interval standard (1788), I consider this as
        largely justified on that basis alone.

        The rest seems just fine to me on a cursory look.

        Enjoy,

                                Dan


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