constants.h

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// Copyright (c) FIRST and other WPILib contributors.
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// Copyright (c) 2016 Nic Holthaus
//
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#pragma once
 
#include "units/area.h"
#include "units/capacitance.h"
#include "units/charge.h"
#include "units/current.h"
#include "units/dimensionless.h"
#include "units/energy.h"
#include "units/force.h"
#include "units/impedance.h"
#include "units/length.h"
#include "units/magnetic_field_strength.h"
#include "units/mass.h"
#include "units/power.h"
#include "units/substance.h"
#include "units/temperature.h"
#include "units/time.h"
#include "units/velocity.h"
 
namespace units::constants {
/**
 * @name Unit Containers
 * @anchor constantContainers
 * @{
 */
using PI = unit<std::ratio<1>, dimensionless::scalar, std::ratio<1>>;
 
static constexpr const unit_t<PI> pi(
    1);  ///< Ratio of a circle's circumference to its diameter.
static constexpr const velocity::meters_per_second_t c(
    299792458.0);  ///< Speed of light in vacuum.
static constexpr const unit_t<
    compound_unit<cubed<length::meters>, inverse<mass::kilogram>,
                  inverse<squared<time::seconds>>>>
    G(6.67408e-11);  ///< Newtonian constant of gravitation.
static constexpr const unit_t<compound_unit<energy::joule, time::seconds>> h(
    6.626070040e-34);  ///< Planck constant.
static constexpr const unit_t<
    compound_unit<force::newtons, inverse<squared<current::ampere>>>>
    mu0(pi * 4.0e-7 * force::newton_t(1) /
        units::math::cpow<2>(current::ampere_t(1)));  ///< vacuum permeability.
static constexpr const unit_t<
    compound_unit<capacitance::farad, inverse<length::meter>>>
    epsilon0(1.0 / (mu0 * math::cpow<2>(c)));  ///< vacuum permitivity.
static constexpr const impedance::ohm_t Z0(
    mu0* c);  ///< characteristic impedance of vacuum.
static constexpr const unit_t<compound_unit<force::newtons, area::square_meter,
                                            inverse<squared<charge::coulomb>>>>
    k_e(1.0 / (4 * pi * epsilon0));  ///< Coulomb's constant.
static constexpr const charge::coulomb_t e(
    1.6021766208e-19);  ///< elementary charge.
static constexpr const mass::kilogram_t m_e(
    9.10938356e-31);  ///< electron mass.
static constexpr const mass::kilogram_t m_p(1.672621898e-27);  ///< proton mass.
static constexpr const unit_t<
    compound_unit<energy::joules, inverse<magnetic_field_strength::tesla>>>
mu_B(e* h / (4 * pi * m_e));  ///< Bohr magneton.
static constexpr const unit_t<inverse<substance::mol>> N_A(
    6.022140857e23);  ///< Avagadro's Number.
static constexpr const unit_t<compound_unit<
    energy::joules, inverse<temperature::kelvin>, inverse<substance::moles>>>
    R(8.3144598);  ///< Gas constant.
static constexpr const unit_t<
    compound_unit<energy::joules, inverse<temperature::kelvin>>>
    k_B(R / N_A);  ///< Boltzmann constant.
static constexpr const unit_t<
    compound_unit<charge::coulomb, inverse<substance::mol>>>
F(N_A* e);  ///< Faraday constant.
static constexpr const unit_t<
    compound_unit<power::watts, inverse<area::square_meters>,
                  inverse<squared<squared<temperature::kelvin>>>>>
    sigma((2 * math::cpow<5>(pi) * math::cpow<4>(R)) /
          (15 * math::cpow<3>(h) * math::cpow<2>(c) *
           math::cpow<4>(N_A)));  ///< Stefan-Boltzmann constant.
/** @} */
}  // namespace units::constants