#ifndef BOOST_NUMERIC_INTERVAL_IO_PRECISION_HPP
#define BOOST_NUMERIC_INTERVAL_IO_PRECISION_HPP

#include <boost/numeric/interval/interval.hpp>
#include <boost/io/ios_state.hpp>
#include <cmath>

namespace boost {
namespace numeric {

template<class T, class Policies, class CharType, class CharTraits>
std::basic_ostream<CharType, CharTraits> &operator<<
  (std::basic_ostream<CharType, CharTraits> &stream,const interval<T, Policies> &value)
{
  const T abs_lower=value.lower()>=0 ? value.lower() : -value.lower();
  const T abs_upper=value.upper()>=0 ? value.upper() : -value.upper();
  const T lower_mantissa=value.lower()/std::pow(10,static_cast<int>(std::log10(abs_lower)+0.5));
  const T upper_mantissa=value.upper()/std::pow(10,static_cast<int>(std::log10(abs_upper)+0.5));

  const T difference=upper_mantissa-lower_mantissa;

  const double exponent=std::log10(difference);

  boost::io::ios_precision_saver state(stream,-exponent+0.5);

  return stream << (value.upper()+value.lower())/2;
}

} // namespace numeric
} // namespace boost

#endif // BOOST_NUMERIC_INTERVAL_IO_PRECISION_HPP