#include <string>
#include <boost/units/conversion.hpp>
#include <boost/units/base_unit.hpp>
#include <boost/units/quantity.hpp>
#include <boost/units/unit.hpp>
#include <boost/units/make_system.hpp>
#include <boost/units/physical_dimensions/length.hpp>
#include <boost/units/base_units/si/meter.hpp>

namespace boost {

namespace units {

namespace nautical {

struct length_base_unit : 
    base_unit<length_base_unit, length_dimension, 1>
{
    static std::string name()       { return "nautical mile"; }
    static std::string symbol()     { return "nmi"; }
};

typedef make_system<length_base_unit>::type system;

typedef unit<length_dimension,system>    length;
typedef unit<dimensionless_type,system>    dimensionless;

static const length mile,miles;

}
}
}

BOOST_UNITS_DEFINE_CONVERSION_FACTOR(boost::units::nautical::length_base_unit,
                                     boost::units::si::meter_base_unit,
                                     double, 1.852e3);

int main()
{
    using namespace boost::units;

    typedef quantity<boost::units::nautical::length> TDistanceInNMI;
    typedef quantity<boost::units::nautical::dimensionless> TDimLess;

    TDistanceInNMI nm1, nm2, nm3;
    TDimLess d;

    nm1 = nm2 + nm3;
    nm1 = d*nm2;
    nm1 = nm2 + d*nm3;

    return 0;
}