Re: [Boost-users] question about boost::interval

From: Marco Correia (mvc_at_[hidden])
Date: 2007-02-21 04:48:54

On Wednesday 21 February 2007 09:27, Guillaume Melquiond wrote:
> Le mardi 20 février 2007 à 18:56 +0000, Marco Correia a écrit :
> > Hi,
> >
> > I'm a little bit confused about the documentation in
> > http://www.boost.org/libs/numeric/interval/doc/rounding.htm, in the
> > subsection "Transcendental functions". Does the "Please note" paragraph
> > means that the provided classes for transcendal functions (_opp and _std)
> > do not guarantee the inclusion property?
>
> Yes.
>
> > >From what I understood it says that it depends on the implementation of
> > > the
> >
> > std::* math functions, that, in most cases, don't obey current rounding
> > mode. Am I getting this right?
>
> Yes.
>
> > In case I am, does anyone knows if I'm safe with gcc std library (perhaps
> > by using the -frounding-math switch)?
>
> No, unfortunately.
>
> You have to rely either on a library that provides functions rounded in
> accordance with the rounding mode of the processor like Sun's libmcr, or
> on a library that provides functions with explicit rounding direction
> like MPFR or CRlibm. The transc.cpp example file of the library shows
> how to write a class relying on MPFR; for Boost 1.35, it may be
> replaced / extended with a class relying on CRlibm.
>
> Best regards,
>
> Guillaume
>
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Thanks a lot!
Marco

-- 
Marco Correia <mvc_at_[hidden]>