2011/10/20 John Maddock <boost.regex@virgin.net>
A thought came to my mind... Theoretically, is it possible for the
following conditions to be true? static_cast<float>( std::numeric_limits<int>::min(**) ) < std::numeric_limits<int>::min(**) static_cast<double>( std::numeric_limits<int>::min(**) ) < std::numeric_limits<int>::min(**) static_cast<long double>( std::numeric_limits<int>::min(**) ) < std::numeric_limits<int>::min(**) static_cast<float>( std::numeric_limits<int>::max(**) ) > std::numeric_limits<int>::max(**) static_cast<double>( std::numeric_limits<int>::max(**) ) > std::numeric_limits<int>::max(**) static_cast<long double>( std::numeric_limits<int>::max(**) ) > std::numeric_limits<int>::max(**) After all, casting to floating-point may loose precision... I have no knowledge in this area, so it may be just a silly thought.
Ah, yes: when I fixed this bug I had to disable some of new the tests for type float because of that very issue: an integer type converted to type float may actually be outside the range of an integer due to rounding during the conversion.
John.
Ah, thanks for a confirmation... I am interested in a resolution here, which I would like to implement in a function I wrote as a more general iround; I call it round_cast(): <code> template < class R, class T, class Policy > inline R round_cast( T const& x, Policy const& pol ) { BOOST_MATH_STD_USING T r = boost::math::round(x,pol); if( r > boost::integer_traits<R>::const_max || r < boost::integer_traits<R>::const_min ) return static_cast<R>( boost::math::policies::raise_rounding_error( "cz::ar::round_cast<target_type,%1%>(%1%)", 0, x, pol ) ); return static_cast<R>(r); } template < class R, class T > inline R round_cast( T const& x ) { return round_cast<R>( x, boost::math::policies::policy<>() ); } </code> Regards Kris