exemple.cpp

// -------------------------------------------------------//
//
// SHAMROCK code for hydrodynamics
// Copyright (c) 2021-2026 Timothée David--Cléris <tim.shamrock@proton.me>
// SPDX-License-Identifier: CeCILL Free Software License Agreement v2.1
// Shamrock is licensed under the CeCILL 2.1 License, see LICENSE for more information
//
// -------------------------------------------------------//
 
#include <shamunits/Constants.hpp>
#include <shamunits/UnitSystem.hpp>
#include <iostream>
 
// g++ -std=c++17 -Iinclude exemple.cpp
 
int main(void) {
 
    using namespace shamunits;
 
    // create si units
    UnitSystem<double> si{};
 
    // get the value of au^2 in the unit system
    // but it is quite big :)
    std::cout << si.get<units::astronomical_unit, 2>() << std::endl;
 
    double sol_mass = Constants<double>(si).sol_mass();
 
    /*
     * create a unit system with time in Myr, length in au, mass in solar masses
     */
    UnitSystem<double> astro_units{
        si.get<mega, units::years>(),
        si.get<units::astronomical_unit>(),
        si.get<units::kilogram>() * sol_mass,
    };
 
    // this time it returns 1 because the base length is the astronomical unit
    std::cout << astro_units.get<units::astronomical_unit, 2>() << std::endl;
 
    Constants<double> astro_cte{astro_units};
 
    // in those units G is 3.94781e+25
    std::cout << astro_cte.G() << std::endl;
}