Fwd: (j3.2004) [Fwd: [Numeric-interest] correctly rounded LIBM subset]

[Craig Rasmussen]

Is this library of any interest to gfortran developers?

Regards,
Craig


Begin forwarded message:

> From: Keith Bierman <Keith.Bierman@sun.com>
> Date: November 30, 2004 3:26:55 PM MST
> To: "'J3 Fortran'" <j3@j3-fortran.org>
> Cc: Subject: (j3.2004) [Fwd: [Numeric-interest] correctly rounded LIBM 
> subset]
>
>
> I know this isn't Fortran specific (nor even coded in Fortran) but I 
> thought it might be of interest to some of you.
> -------- Original Message --------
> Subject: 	[Numeric-interest] correctly rounded LIBM subset
> Date: 	Tue, 30 Nov 2004 12:18:28 -0800 (PST)
> From: 	Neil Toda <ntt@cubmeister.sfbay.sun.com>
> To: 	numeric-interest@oakapple.net
>
>
>
> Kwok-Choi Ng of Sun Microsystems' Floating Point Libraries group has
> put together a correctly-rounded double-precision subset of libm
> consisting of seven elementary transcendental functions. The rounding
> direction can be set to any of the four rounding directions specified
> by IEEE-754.  The library is distributed as source with makefiles to
> build it, and a set of tests to check the library's basic functioning.
>
> Current development in the field of correctly-rounded libm functions 
> are
> generally aimed at replacing vendor supplied libraries that are
> advertised to be nearly correctly rounded, returning results with
> maximum errors not much larger than  .5 ULPs.  These algorithms are of
> course concerned with performance, both average, and for worse case
> situations.  For these attempts, a multi-stage approach seems to show
> greatest promise:
> A lower precision computation first, followed by a computation with
> significantly more precision if the original step did not yield a 
> result
> that could be judged correctly rounded.  However, to set an upper limit
> for the precision used, that precision must be proved sufficient to
> allow correct rounding of the result: Still an active research topic.
> The functions of LIBMCR are designed to attempt solutions at lower
> precisions, but will continue, adding precision until the result can
> be correctly rounded.  Clearly, while these algorithms will return
> correctly rounded results, there is no guarantee as to the maximum
> computer-power/memory-load necessary to complete a calculation,
>
> For this reason, LIBMCR is not considered a candidate for a production
> level library, but rather a tool that can be used to further study/test
> efforts in correctly rounding the elementary transcendental functions.
>
> The library is available through Sun-Developer's "Whats New" portal:
>
> 	http://developers.sun.com/prodtech/cc/
>
> LIBMCR is supported by Sun's Floating Point Libraries group and
> feedback is welcomed and can be sent to :
>
> 	libmcr-comments-2004 AT sun DOT com
>
>
>
> ======================\|/==============================================
> === Neil T Toda     -- o -- Sun Microsystems Inc  |   FP Lib Group  ===
> === Neil.Toda@Sun.com /|\      Menlo Park, Ca     |   M/S MPK16-303 ===
> =======================================================================
>
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