#include <iostream>

#include "boost/units/systems/si.hpp"
#include "boost/units/systems/si/io.hpp"

using boost::units::quantity;
using boost::units::si::torque;
using boost::units::si::newton_meter;
using boost::units::si::newton;
using boost::units::si::meter;
using boost::units::si::radian;

int main()
{
    // works fine:
    quantity<torque, double> tau0 = 0.0 * newton_meter;

    // SURPRISE: compilation fails because newton_meter is not the
    // same as newton*meter!
//    quantity<torque, double> tau1 = 0.0 * newton * meter;

    // Compilation succeeds even though the units on the RHS do not
    // represent torque but torsional stiffness!
    quantity<torque, double> tau2 = 0.0 * newton * meter / radian;

    // newton * meter should give us a quantity with units of Newton-
    // meters, i.e. m^2 kg s^-2.  What this actually prints out is "0 J",
    // which is reasonable since dimensionally J is the same as N m.
    std::cout << boost::units::to_string(0.0 * newton * meter) << std::endl;

    // One might hope that newton_meter would be the same thing as
    // newton * meter.  Instead, the result is "0 m^2 kg s^-2 rad^-1"
    std::cout << boost::units::to_string(0.0 * newton_meter) << std::endl;

    // The "torque" unit is also messed up in the same way.
    std::cout << boost::units::to_string(torque()) << std::endl;
}