Re: [Boost-bugs] [Boost C++ Libraries] #1632: Default Interval rounding policies incomplete

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #1632: Default Interval rounding policies incomplete
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-05-24 16:15:02

#1632: Default Interval rounding policies incomplete
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  Reporter:  Steven Robbins <smr_at_[hidden]>  |       Owner:  no-maintainer
      Type:  Bugs                             |      Status:  new          
 Milestone:  Boost 1.36.0                     |   Component:  numeric      
   Version:  Boost 1.34.1                     |    Severity:  Problem      
Resolution:                                   |    Keywords:               
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Comment (by Ben Galehouse <bgalehouse_at_[hidden]>):

 According to the documentation at
 http://www.boost.org/doc/libs/1_35_0/libs/numeric/interval/doc/rounding.htm

 in the "transcendental function" section, the standard library routines
 for tan, etc, do not typically satisfy the needed rounding properties and
 therefore the templates which implement them are disabled by default.

 I have used tan with the interval library. If you pass it a policy based
 on rounded_transc_std, it works fine.
 e.g. I have written a rounded_control specialization for the mpfr_class
 type from the gmpfrxx interface to mpfr.
 (http://math.berkeley.edu/~wilken/code/gmpfrxx/) With it I can declare the
 specialization
 {{{
 template<>
 struct rounded_math<mpfr_class>
   : save_state_nothing<rounded_transc_std<mpfr_class> >
 {};
 }}}
 and then code like
 {{{
  j =  boost::numeric::interval<mpfr_class> (0.1,0.2);
   j = boost::numeric::tan(j);

   std::cout << "[" << j.lower() << "," << j.upper() << "]" << "\n";
 }}}

 compiles, executes, and gives plausible looking results. Therefore, I
 think this is working as designed.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1632#comment:3>
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