rs-core

Core utilities

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Physical constants

Core utility library by Ross Smith

#include "rs-core/constants.hpp"
namespace RS;

Contents

Introduction

All of the constants defined here follow the conventions of the standard <numbers> header. Each constant is defined in two forms:

constexpr double name = [value as double];
template <std::floating_point T> constexpr T name_v = [value as T];

For the physical and astronomical constants, long and short versions of the constant names are provided. The short names (but not the full names) are in the RS::Constants sub-namespace to avoid name collisions when the symbols are not needed.

The values quoted here are illustrative, mostly quoted to 4 significant figures. The values actually supplied in the header are accurate to the precision of the type or to the best known precision, whichever is appropriate.

Conversion factors

Constant Value
arcsec 4.848×10-6 rad
arcmin 2.909×10-4 rad
degree 0.01745 rad
inch 0.0254 m
foot 0.3048 m
yard 0.9144 m
mile 1609 m
nautical_mile 1852 m
ounce 0.02835 kg
pound 0.4536 kg
short_ton 907.2 kg
long_ton 1016 kg
pound_force 4.448 N
erg 10-7 J
foot_pound 1.356 J
calorie 4.184 J
kilocalorie 4184 J
ton_tnt 4.184×109 J
horsepower 745.7 W
mmHg 133.3 Pa
atmosphere 101300 Pa
zero_celsius 273.15 K

Physical constants

Sources:

Constant Symbol Value
alpha_particle_mass m_alpha 6.645×10-27 kg
atomic_mass_constant m_u 1.661×10-27 kg
avogadro_constant N_A 6.022×1023 mol-1
boltzmann_constant k 1.381×10-23 J/K
electron_mass m_e 9.109×10-31 kg
elementary_charge ec 1.602×10-19 C
fine_structure_constant alpha 7.297×10-3 dimensionless
first_radiation_constant c_1 3.742×10-16 W m2
gravitational_constant G 6.674×10-11 m3 kg-1 s-2
josephson_constant K_J 4.836×1014 Hz V-1
molar_gas_constant R 8.314 J mol-1 K-1
neutron_mass m_n 1.675×10-27 kg
planck_constant h 6.626×10-34 J s
proton_mass m_p 1.673×10-27 kg
rydberg_constant R_inf 1.097×107 m-1
second_radiation_constant c_2 0.01439×10-2 m K
speed_of_light c 2.998×108 m/s
stefan_boltzmann_constant sigma 5.670×10-8 W m-2 K-4
vacuum_impedance Z_0 376.7 Ω
vacuum_permeability mu_0 1.257×10-6 N A-2
vacuum_permittivity epsilon_0 8.854×10-12 F m-1
von_klitzing_constant R_K 25810 Ω
wien_constant b_W 2.898×10-3 m K