[Cfp-interest] WG14 IEEE 754-C binding meeting minutes 2018/04/10

Tue Apr 10 14:27:25 PDT 2018

  Attendees: Rajan, Jim, Mike, David H., Ian

  New agenda items:
    exp10m1 range error

  Last meeting action items:
    Ian: See if there is an incompatibility between C and C++ for 
constants being evaluated to a wider format (Ex. FLT_EVAL_METHOD affects 
constants in C++, and wider return values) - Keep open (Hubert: Not 
defined and left up to C)
    Jim: Update the binding table in parts 1 and 2 to handle the new 
IEEE-754:2018 functions when published. - Keep open.
    Jim: Update activities list. 
    David: Look into the IEEE binding differences to see if they are real 
issues (from Fred's email on 2018/02/18). - Done.
 
    Jim: Create a DR against part 1 for updating C footnote 232 as per 
emails on 2018/02/22. - Done.
    Jim: Obsolescing DECIMAL_DIG (
http://wiki.edg.com/pub/CFP/WebHome/changes_for_obsolescing_DECIMAL_DIG-20180306.pdf
): Change 1: Change "decimal" to "decimal character sequence" throughout 
the document to avoid confusion with DFP. Also need to qualify it with the 
rounding mode. - Done.
    Jim: Obsolescing DECIMAL_DIG (
http://wiki.edg.com/pub/CFP/WebHome/changes_for_obsolescing_DECIMAL_DIG-20180306.pdf
): Change TS 18661-1 10.1: Needs the round to nearest rounding mode text 
as per the previous action item. - Done.
    Jim: Obsolescing DECIMAL_DIG (
http://wiki.edg.com/pub/CFP/WebHome/changes_for_obsolescing_DECIMAL_DIG-20180306.pdf
): Change TS 18661-1 10.1: Typo: IEC 60669 -> IEC 60559 - Done.
    Jim: Obsolescing DECIMAL_DIG (
http://wiki.edg.com/pub/CFP/WebHome/changes_for_obsolescing_DECIMAL_DIG-20180306.pdf
): Get a document number and submit in time for the mailing if possible. - 
Done.
    Jim: TS DR16: Remove the cbrt examples in parts 2 and 3 for cbrt as 
part of DR16 as a note for an editorial change. - Done.
    Jim: TS DR13: 
http://wiki.edg.com/pub/CFP/WebHome/Re-revised_suggested_TC_for_CFP_DR_13-20180223.pdf: 
Send it out (with fixes to the font/alignment). - Done.
    Jim: Reword 
http://wiki.edg.com/pub/CFP/WebHome/NaN_payload_functions_for_C-20180311.pdf 
F.10.13 description to say something along the lines of "a floating point 
number with an unsigned integer value" and for the function descriptions 
as well. - Done.
    Fred: http://wiki.edg.com/pub/CFP/WebHome/in_flight-20180313.pdf: See 
where we are for inconsistent spec for infinities. - Not Done.
    Fred: http://wiki.edg.com/pub/CFP/WebHome/in_flight-20180313.pdf: See 
where we are for missing Annex F spec for new functions. - Done.
    Jim: Working drafts: Try red strike-through for parts 2-5 and red 
caret for part 1. - Done.
 
  New action items:
    Jim: Look at what is said in exception handling and make sure 
remainder underflow is addressed as per Jim's/Fred/David's email regarding 
18661-1 and 754 (2018/04/09). 
    Jim: 754 compatibility: roundeven: Put in the parenthetical 
(conclusion) into part 1 as per Jim's response to David on the 2018/04/09 
email.
    David: Check the min/max C specification to ensure it matches what 
IEEE has.
    David: Check the augmented* C function specifications to ensure they 
match what IEEE has.
    David: Evaluate the 18661-4 tanpi and ensure it is not a bad idea. 
Also ask 754 what we (CFP) should do with it.
    All: Look at Fred's 2018/02/19 email titled "18661-2 and 754".
    Jim: Integrate the 2018/04/05 DR13 change into N2213 and get a new N 
document so we can talk to that in WG14.
    Jim: Part 4: Change the exp10m1 description to allow underflow range 
errors.
 
  Next Meeting(s):
    Tuesday May 22nd 2018, 12:00 EDT, 9:00 PST
    Same teleconference number.

  Discussion:
    IEEE 754 revision:
      Nearing the end, but some things still coming up.
      Mostly delaying larger items until the next revision (2028?).
      Telecon every 3 weeks.
      Differences list is up to date (http://754r.ucbtest.org/changes.html
).
        We will use it as a reference to communicate it to WG14.
 
    C++ liaison:
      Nothing.
 
    Action item details:
      DR for updating underflow definition (
http://wiki.edg.com/pub/CFP/WebHome/n2210.pdf):
        Looks OK.
 
      Changes for obsolescing DECIMAL_DIG (
http://wiki.edg.com/pub/CFP/WebHome/n2211.pdf):
        Jim: Some cleanup of wording in the C standard to help clear up 
confusion.
        The changes in the library are not as big as they look since this 
shows the context.
        Some changes are not needed if Part 1 is accepted into C22 (C11 
F.5 heading for example).
 
      Revised suggested TC for CFP DR 16 (
http://wiki.edg.com/pub/CFP/WebHome/n2212.pdf):
        Note that parts 2 and 3 examples will be removed as listed.
 
      Re-revised suggested TC for CFP DR 13 (
http://wiki.edg.com/pub/CFP/WebHome/n2213.pdf):
        Will discuss later.
 
      Update to payload functions (
http://wiki.edg.com/pub/CFP/WebHome/NaN_payload_functions_for_C-20180328.pdf
):
        Looks good.
 
      IEEE binding differences (from Fred's email on 2018/02/18):
        See Jim's response email on 2018/04/09.
 
        Underflow issues (Jim/Fred/David's emails for 754 compatibility):
          Part 5 alternate exception handling may handle this.
            Some underflow exceptions that were not detectable before can 
now be detectable.
            *Jim: Look at what is said in exception handling and make sure 
remainder underflow is addressed as per Jim's/Fred/David's email regarding 
18661-1 and 754 (2018/04/09).
          *Jim: roundeven: Put in the parenthetical (conclusion) into part 
1.
          canonicalize: Looks good.
          fesetexcept: Jim: The other interfaces don't return the set of 
flags so we shouldn't change this one. Also to match C, need to leave it 
as is.
          fetestexceptflag: Seems right as it is. Order of arguments is to 
match C.
 
      Inconsistent spec for infinities:
        Pending.
 
      Missing annex F spec for new functions (Fred 3/17/18 email 
"[Cfp-interest] IEEE 754 vs Annex F":
        See Jim's response on 2018/04/10 as well.
 
        Re point 2: cospi(0): The new IEEE spec does specify this even 
though it is not necessary.
        tanpi: IEEE didn't do it due to cases of 0 having the right sign. 
David to look at it.
          Not sure which properties are the most important nor if it 
matters.
        pown: David: Obvious, but will add it to the 754 agenda to discuss 
adding it.
 
        Still need to look at Fred's 2018/02/19 email titled "18661-2 and 
754".
 
      Change marks for working drafts:
        Looks OK.
 
    Other issues:
      Joseph Myers 3/19 email (SC22WG14.14928) Floating-point DR#13 and 
integer arguments to type-generic macros
        See Jim's 2018/04/05 response to CFP.
        Will need to show this as part of 7.4.1 in the WG14 meeting. Can 
make it harder to argue to add part 3 into the standard.
        *Jim: Integrate this change into N2213 and get a new N document so 
we can talk to that in WG14.
 
      exp10m1 range error (Fred's email on 2018/02/20): 
        Jim: Change this to allow underflow range errors for this case.
 
 
    Binding for IEEE 754-2018:
      WG14 paper about updating to IEEE 754:2018
        Rajan can mention we are ready to go based on David's change list 
and our updated proposals for min/max and augmented.
 
      Functions for augmented arithmetic
 
      Min/max functions
 
      Payload functions
 
      Total order functions
 

    C2X integration:
      Jim looking at tutorials about LaTeX.
 
    Activities (http://wiki.edg.com/pub/CFP/WebHome/in_flight-20180313.pdf
):
      No update.
 
    Deferred issues:
      C standard use of "floating" vs "floating-point":
        Delay until later.
 
  CFP Report for WG14 meeting:
    Continuing to work on DR's to the TS.
    Continuing to work on IEEE 754:2018 binding.
    Looking for other possible issues when comparing binding to 754:2008 
to validate we are binding correctly.
 

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