Re: [boost] [xint] Boost.XInt formal review

Subject: Re: [boost] [xint] Boost.XInt formal review
From: Paul A. Bristow (pbristow_at_[hidden])
Date: 2011-03-11 13:43:32

> -----Original Message-----
> From: boost-bounces_at_[hidden] [mailto:boost-bounces_at_[hidden]]
> On Behalf Of Kim Barrett
> Sent: Friday, March 11, 2011 5:56 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] [xint] Boost.XInt formal review
> 
> Not really about XInt, but responding to a side comment in Paul Bristow's
> review.
> 
> On Mar 11, 2011, at 5:12 AM, Paul A. Bristow wrote:
> > A possible using-xint project (GSoC?) might be implementation of
> > reading floating point (which require big (-ish) integers) of William
> > D. Clinger
> >
> > http://www.cesura17.net/~will/Professional/Research/Papers/howtoread.p
> > df
> >
> > http://portal.acm.org/citation.cfm?id=93557
> >
> > and writing FP by Steele and White
> >
> > http://grouper.ieee.org/groups/754/email/pdfq3pavhBfih.pdf
> >
> > I am sure that there are many others.
> 
> 
> The Grisu algorithm family doesn't require bignums.  The results are
better (as in
> "shorter") if there are more bits in the (fixed) integer representation
than in the
> floating point significand.  The paper focuses on printing IEEE doubles
using 64
> bit integers.  According to the paper, Grisu2 produces the shortest output
for
> approximately 99.9% of the inputs, and a longer but still correct output
> otherwise.  Grisu3 (intended for use when shortest output is a
requirement)
> produces the shortest result for 99.5% of IEEE doubles, providing a
failure
> indication on the remainder so that one can fall back to some other
algorithm
> (such as Steele & White's Dragon4, which does require bignums).
> 
> Printing Floating-Point Numbers Quickly and Accurately with Integers
Florian
> Loitsch
> PLDI'10

Looks most interesting, but I don't have access to ACM.  Can anyone provide
the pdf for my private study ;-)

Does anyone think using this for a Boost C++ version is a GSoC project, or
are there patent or other IP issues?

Thanks

Paul