arts_constants.h

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#ifndef CONSTANTS_IN_ARTS_H
#define CONSTANTS_IN_ARTS_H
 
#include <numbers>
 
#include "arts_constexpr_math.h"
#include "matpack_concepts.h"
 
namespace Constant {
inline constexpr Numeric pi = std::numbers::pi;
 
inline constexpr Numeric inv_pi = std::numbers::inv_pi;
 
inline constexpr Numeric two_pi = 2 * pi;
 
inline constexpr Numeric inv_two_pi = 0.5 * inv_pi;
 
inline constexpr Numeric sqrt_pi = 1.0/std::numbers::inv_sqrtpi;
 
inline constexpr Numeric inv_sqrt_pi = std::numbers::inv_sqrtpi;
 
inline constexpr Numeric euler = std::numbers::e;
 
inline constexpr Numeric inv_euler = 1.0 / euler;
 
inline constexpr Numeric log10_euler = std::numbers::log10e;
 
inline constexpr Numeric ln_10 = std::numbers::ln10;
 
inline constexpr Numeric sqrt_2 = std::numbers::sqrt2;
 
inline constexpr Numeric inv_sqrt_2 = 1.0 / sqrt_2;
 
inline constexpr Numeric ln_2 = std::numbers::ln2;
 
inline constexpr Numeric inv_ln_2 = 1.0 / ln_2;
 
inline constexpr Numeric sqrt_ln_2 =
    0.8325546111576977563531646448952010476305888522644407291668291172340794351973;
 
inline constexpr Numeric inv_sqrt_ln_2 =
    1.201122408786449794857803286095221722566764028068699423868879896733837175546;
 
inline constexpr Numeric Delta_nu_Cs = 9192631770;
 
inline constexpr Numeric speed_of_light = 299792458;
 
inline constexpr Numeric c = speed_of_light;
 
inline constexpr Numeric planck_constant = 6.62607015e-34;
 
inline constexpr Numeric h = planck_constant;
 
inline constexpr Numeric reduced_planck_constant = h * inv_two_pi;
 
inline constexpr Numeric h_bar = reduced_planck_constant;
 
inline constexpr Numeric elementary_charge = 1.602176634e-19;
 
inline constexpr Numeric e = elementary_charge;
 
inline constexpr Numeric boltzmann_constant = 1.380649e-23;
 
inline constexpr Numeric k = boltzmann_constant;
 
inline constexpr Numeric avogadro_constant = 6.02214076e23;
 
inline constexpr Numeric NA = avogadro_constant;
 
inline constexpr Numeric K_cd = 683;
 
inline constexpr Numeric fine_structure_constant = 7.2973525693e-3;
 
inline constexpr Numeric alpha = fine_structure_constant;
 
inline constexpr Numeric rydberg_constant = 10973731.568160;
 
inline constexpr Numeric R_inf = rydberg_constant;
 
inline constexpr Numeric magnetic_constant = 2 * h * alpha / (c * Math::pow2(e));
 
inline constexpr Numeric mu_0 = magnetic_constant;
 
inline constexpr Numeric vacuum_permittivity = Math::pow2(e) / (2 * h * c * alpha);
 
inline constexpr Numeric epsilon_0 = vacuum_permittivity;
 
inline constexpr Numeric electron_mass = 2 * h * R_inf / (c * Math::pow2(alpha));
 
inline constexpr Numeric m_e = electron_mass;
 
inline constexpr Numeric unified_atomic_mass_unit = 1.66053906660e-27;
 
inline constexpr Numeric m_u = unified_atomic_mass_unit;
 
inline constexpr Numeric mass_ratio_electrons_per_proton = 1'836.152'673'43;
 
inline constexpr Numeric proton_mass =
    electron_mass * mass_ratio_electrons_per_proton;
 
inline constexpr Numeric mass_ratio_electrons_per_neutron = 1'838.683'661'73;
 
inline constexpr Numeric neutron_mass =
    electron_mass * mass_ratio_electrons_per_neutron;
 
inline constexpr Numeric bohr_magneton = e * h_bar / (2 * m_e);
 
inline constexpr Numeric ideal_gas_constant = k * NA;
 
inline constexpr Numeric R = ideal_gas_constant;
 
inline constexpr Numeric doppler_broadening_const_squared = 2'000 * R / Math::pow2(c);
 
inline constexpr Numeric one_degree_in_radians = pi / 180;
 
inline constexpr Numeric stefan_boltzmann_constant =
    Math::pow2(pi) * Math::pow4(k) / (Math::pow3(h_bar) * Math::pow2(c)) / 60.;
 
inline constexpr Numeric sigma = stefan_boltzmann_constant;
 
inline constexpr Numeric density_of_ice_at_0c = 0.9167e3;
 
inline constexpr Numeric denity_of_water_at_4c = 1e3;
 
inline constexpr Numeric cosmic_microwave_background_temperature = 2.735;
 
inline constexpr Numeric earth_radius = 6.3781e6;
 
inline constexpr Numeric temperature_at_0c = 273.15;
};  // namespace Constant
 
#endif