units.hpp

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/** \file units.hpp
 * \author Jared R. Males (jaredmales@gmail.com)
 * \brief Unit specifications and conversions.
 * \ingroup astrofiles
 *
 */
 
#ifndef __mx_astro_units_hpp__
#define __mx_astro_units_hpp__
 
#include "constants.hpp"
 
namespace mx
{
 
namespace astro
{
 
namespace units
{
 
/** \defgroup astrounits Unit Conversions
 * \brief Definitions of unit coversions for physical constants.
 * \ingroup phyconstants
 *
 * These types provide the ratios to convert from SI units to the desired system.
 *
 * @{
 */
 
/// International System of Units (SI) units-type
/** Since all constants are specified in SI units, all conversions here are 1.0.
 */
template <typename _realT>
struct si
{
    typedef _realT realT; ///< The real floating point type in which to specify constants.
    static constexpr realT length = static_cast<realT>( 1.0 );      ///< Conversion from SI (m) to SI (m)
    static constexpr realT time = static_cast<realT>( 1.0 );        ///< Conversion from SI (s) to SI (s)
    static constexpr realT mass = static_cast<realT>( 1.0 );        ///< Conversion from SI (kg) to SI (kg)
    static constexpr realT energy = static_cast<realT>( 1.0 );      ///< Conversion from SI (J) to SI (J)
    static constexpr realT temperature = static_cast<realT>( 1.0 ); ///< Conversion from SI (K) to SI (K)
};
 
/// Centimeter-Gram-Second (cgs) units-type
/** The units are:
 * - Length: centimeter (cm)
 * - Time: second (s)
 * - Mass: gram (g)
 * - Energy: erg (erg)
 * - Temperature: Kelvin (K)
 */
template <typename _realT>
struct cgs
{
    typedef _realT realT; ///< The real floating point type in which to specify constants.
    static constexpr realT length = static_cast<realT>( 100.0 );    ///< Conversion from SI (m) to cgs (cm)
    static constexpr realT time = static_cast<realT>( 1.0 );        ///< Conversion from SI (s) to cgs (s)
    static constexpr realT mass = static_cast<realT>( 1000.0 );     ///< Conversion from SI (kg) to cgs (g)
    static constexpr realT energy = static_cast<realT>( 1e7 );      ///< Conversion from SI (J) to cgs (erg)
    static constexpr realT temperature = static_cast<realT>( 1.0 ); ///< Conversion from SI (K) to cgs (K)
};
 
/// Solar units-type
/** The units are:
 * - Length: au
 * - Time: year
 * - Mass: solar mass
 * - Energy: solar-luminosity-year
 * - Temperature: solar effective temperature
 */
template <typename _realT>
struct solar
{
    typedef _realT realT; ///< The real floating point type in which to specify constants.
    static constexpr realT length =
        static_cast<realT>( 1 ) / constants::au<si<realT>>(); ///< Conversion from SI (m) to solar (au)
    static constexpr realT time =
        static_cast<realT>( 1.0 ) / constants::year<si<realT>>(); ///< Conversion from SI (s) to solar (yr)
    static constexpr realT mass =
        constants::G<si<realT>>() / constants::GMSun<si<realT>>(); ///< Conversion from SI (kg) to solar (M_sun)
    static constexpr realT energy =
        static_cast<realT>( 1.0 ) /
        ( constants::lumSun<si<realT>>() * static_cast<realT>( 365.25 ) *
          static_cast<realT>( 86400.0 ) ); ///< Conversion from SI (J) to  solar (Solar-luminosities X year)
    static constexpr realT temperature =
        static_cast<realT>( 1.0 ) / constants::TeffSun<si<realT>>(); ///< Conversion from SI (K) to solar (5772 K)
};
 
/// Earth units-type
/** The units are:
 * - Length: Earth-radii
 * - Time: s
 * - Mass: Earth mass
 * - Energy: J
 * - Temperature: K
 */
template <typename _realT>
struct earth
{
    typedef _realT realT; ///< The real floating point type in which to specify constants.
    static constexpr realT length =
        static_cast<realT>( 1 ) / constants::radEarth<si<realT>>(); ///< Conversion from SI (m)
    static constexpr realT time = static_cast<realT>( 1.0 );        ///< Conversion from SI (s)
    static constexpr realT mass =
        static_cast<realT>( 1.0 ) / constants::massEarth<si<realT>>(); ///< Conversion from SI (kg)
    static constexpr realT energy = static_cast<realT>( 1.0 );         ///< Conversion from SI (J)
    static constexpr realT temperature = static_cast<realT>( 1.0 );    ///< Conversion from SI (K)
};
 
/// Jupiter units-type
/** The units are:
 * - Length: Jupiter-radii
 * - Time: s
 * - Mass: Jupiter mass
 * - Energy: J
 * - Temperature: K
 */
template <typename _realT>
struct jupiter
{
    typedef _realT realT; ///< The real floating point type in which to specify constants.
    static constexpr realT length =
        static_cast<realT>( 1 ) / constants::radJupiter<si<realT>>(); ///< Conversion from SI (m)
    static constexpr realT time = static_cast<realT>( 1.0 );          ///< Conversion from SI (s)
    static constexpr realT mass =
        static_cast<realT>( 1.0 ) / constants::massJupiter<si<realT>>(); ///< Conversion from SI (kg)
    static constexpr realT energy = static_cast<realT>( 1.0 );           ///< Conversion from SI (J)
    static constexpr realT temperature = static_cast<realT>( 1.0 );      ///< Conversion from SI (K)
};
 
///@}
 
} // namespace units
 
} // namespace astro
} // namespace mx
 
#endif //__mx_astro_units_hpp__