🚀 go-pugleaf

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newsbf01.news.aol.com!newstf01.news.aol.com!uunet!in1.uu.net!news.sprintli
nk.net!howland.reston.ans.net!torn!sq!msb
> 
> I (Mark Brader, msb@sq.com) wrote:
>  
> I was talking about conversions involving integral types, but Paul
Eggert
> (eggert@twinsun.com)'s observation:
> 
> > But what about the common practice of giving programmers run-time (or
> > compile-time) control over the IEEE floating point rounding mode?
> > Doesn't that cause implementation-defined conversions to yield
> > different results for the same value?
> 
> is still relevant since the essence of the matter may be considered to
be
> just what "implementation-defined" means.
> 
> However, a flag used at compile time may be considered as selecting a
> different C implementation (similarly, it is often asserted that the
> ANSIness of gcc depends on whether the flags "-ansi -pedantic" are
used).
> So in that case, the conversion is still constant within a particular
> implementation.
> 
> And ANSI C provides no run-time call to change the IEEE float rounding
> mode; so if a programmer uses such a call, the program is not strictly
> conforming and we don't have to think about it further.

The Floating Point C Extensions (FPCE) which provide, among other things,
a common binding of IEEE arithmetic features to C.  This work was
developed by Jim Thomas and David Hough (?) and many others in X3J11.1
(NCEG - Numeric C Extensions Group) during the past 5 years.  This work is
being considered (developed) for C9X.  This feature provides control of
rounding mode for IEEE implementations.  The proposal is on the WG14
and X3J11 FTP site:

	ftp://ftp.dmk.com/DMK/sc22wg14/c9x/floating-point/fpce.*

-FF
-------------------------------------------------------------------
(``I only use AOL for reading netnews.'')
Frank Farance, Farance Inc.
E-mail: frank@farance.com, Telephone: +1 212 486 4700
ISO JTC1/SC22/WG14 & ANSI X3J11 (C Programming Language) Project Editor