units/tutorial/tutorial_1.cpp

// mcs::units - A C++ library for zero-overhead dimensional analysis and 
// unit/quantity manipulation and conversion
//
// Copyright (C) 2003-2007 Matthias Christian Schabel
// Copyright (C) 2007 Steven Watanabe
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

#include <iostream>

#include <boost/units/base_dimension.hpp>
#include <boost/units/derived_dimension.hpp>
#include <boost/units/io.hpp>
#include <boost/units/quantity.hpp>
#include <boost/units/static_constant.hpp>
#include <boost/units/unit.hpp>
#include <boost/units/base_unit.hpp>
#include <boost/units/make_system.hpp>

namespace boost {

namespace units {

struct length_base_dimension : boost::units::base_dimension<length_base_dimension,1> { };       ///> base dimension of length
struct mass_base_dimension : boost::units::base_dimension<mass_base_dimension,2> { };           ///> base dimension of mass
struct time_base_dimension : boost::units::base_dimension<time_base_dimension,3> { };           ///> base dimension of time

typedef length_base_dimension::type    length_dimension;
typedef mass_base_dimension::type      mass_dimension;
typedef time_base_dimension::type      time_dimension;

struct centimeter_base_unit : base_unit<centimeter_base_unit,length_dimension,1> { };
struct gram_base_unit : base_unit<gram_base_unit,mass_dimension,2> { };
struct second_base_unit : base_unit<second_base_unit,time_dimension,3> { };

namespace CG {

typedef make_system<centimeter_base_unit,
                    gram_base_unit>::type   system;

/// unit typedefs
typedef unit<dimensionless_type,system>     dimensionless;

typedef unit<length_dimension,system>       length;
typedef unit<mass_dimension,system>         mass;

/// unit constants 
BOOST_UNITS_STATIC_CONSTANT(centimeter,length);
BOOST_UNITS_STATIC_CONSTANT(gram,mass);

} // namespace CGS

namespace CGS {

typedef make_system<centimeter_base_unit,
                    gram_base_unit,
                    second_base_unit>::type system;

/// unit typedefs
typedef unit<dimensionless_type,system>     dimensionless;

typedef unit<length_dimension,system>       length;
typedef unit<mass_dimension,system>         mass;
typedef unit<time_dimension,system>         time;

/// unit constants 
BOOST_UNITS_STATIC_CONSTANT(centimeter,length);
BOOST_UNITS_STATIC_CONSTANT(gram,mass);
BOOST_UNITS_STATIC_CONSTANT(second,time);

} // namespace CGS

namespace esu {

typedef make_system<centimeter_base_unit,
                    gram_base_unit,
                    second_base_unit>::type system;

/// derived dimension for force in electrostatic units : L M T^-2
typedef derived_dimension<length_base_dimension,1,
                          mass_base_dimension,1,
                          time_base_dimension,-2>::type                                             force_dimension;
                          
/// derived dimension for charge in electrostatic units : L^3/2 M^1/2 T^-1
typedef make_dimension_list< mpl::list< dim<length_base_dimension,static_rational<3,2> >,
                                        dim<mass_base_dimension,static_rational<1,2> >,
                                        dim<time_base_dimension,static_rational<-1> > > >::type     charge_dimension; 

/// derived dimension for current in electrostatic units : L^3/2 M^1/2 T^-2
typedef make_dimension_list< mpl::list< dim<length_base_dimension,static_rational<3,2> >,
                                        dim<mass_base_dimension,static_rational<1,2> >,
                                        dim<time_base_dimension,static_rational<-2> > > >::type     current_dimension; 

/// derived dimension for electric potential in electrostatic units : L^1/2 M^1/2 T^-1
typedef make_dimension_list< mpl::list< dim<length_base_dimension,static_rational<1,2> >,
                                        dim<mass_base_dimension,static_rational<1,2> >,
                                        dim<time_base_dimension,static_rational<-1> > > >::type     electric_potential_dimension; 

/// derived dimension for electric field in electrostatic units : L^-1/2 M^1/2 T^-1
typedef make_dimension_list< mpl::list< dim<length_base_dimension,static_rational<-1,2> >,
                                        dim<mass_base_dimension,static_rational<1,2> >,
                                        dim<time_base_dimension,static_rational<-1> > > >::type     electric_field_dimension; 

/// unit typedefs
typedef unit<dimensionless_type,system>     dimensionless;

typedef unit<length_dimension,system>       length;
typedef unit<mass_dimension,system>         mass;
typedef unit<time_dimension,system>         time;

typedef unit<force_dimension,system>        force;

typedef unit<charge_dimension,system>               charge;
typedef unit<current_dimension,system>              current;
typedef unit<electric_potential_dimension,system>   electric_potential;
typedef unit<electric_field_dimension,system>       electric_field;

/// unit constants 
BOOST_UNITS_STATIC_CONSTANT(centimeter,length);
BOOST_UNITS_STATIC_CONSTANT(gram,mass);
BOOST_UNITS_STATIC_CONSTANT(second,time);

BOOST_UNITS_STATIC_CONSTANT(dyne,force);

BOOST_UNITS_STATIC_CONSTANT(esu,charge);
BOOST_UNITS_STATIC_CONSTANT(statvolt,electric_potential);

} // namespace esu

template<> struct base_unit_info<centimeter_base_unit>
{
    static std::string name()               { return "centimeter"; }
    static std::string symbol()             { return "cm"; }
};

template<> struct base_unit_info<gram_base_unit>
{
    static std::string name()               { return "gram"; }
    static std::string symbol()             { return "g"; }
};

template<> struct base_unit_info<second_base_unit>
{
    static std::string name()               { return "second"; }
    static std::string symbol()             { return "s"; }
};

template<class Y>
quantity<esu::force,Y> coulombLaw(const quantity<esu::charge,Y>& q1,
                                  const quantity<esu::charge,Y>& q2,
                                  const quantity<esu::length,Y>& r)
{
    return q1*q2/(r*r);
}

} // namespace units

} // namespace boost

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

    quantity<CG::length>    cg_length(1.0*CG::centimeter);
    quantity<CGS::length>   cgs_length(1.0*CGS::centimeter);
    
    std::cout << cg_length/cgs_length << std::endl;

    std::cout << esu::gram*pow<2>(esu::centimeter/esu::second)/esu::esu << std::endl;
    std::cout << esu::statvolt/esu::centimeter << std::endl;
    
    quantity<esu::charge>   q1 = 1.0*esu::esu,
                            q2 = 2.0*esu::esu;
    quantity<esu::length>   r = 1.0*esu::centimeter;
    
    std::cout << coulombLaw(q1,q2,r) << std::endl;
    std::cout << coulombLaw(q1,q2,cgs_length) << std::endl;
    
    return 0;
}