From c60f7c1cfe744948930883017ca8749c7f37d031 Mon Sep 17 00:00:00 2001
From: nholthaus <nholthaus@gmail.com>
Date: Sun, 7 Feb 2016 14:04:30 -0500
Subject: [PATCH] physical constants are in and tested.

---
 include/units.h    | 18 ++++++++++++++----
 unitTests/main.cpp | 27 ++++++++++++++++++++-------
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/include/units.h b/include/units.h
index 92d31fd5..d5e3bd5e 100644
--- a/include/units.h
+++ b/include/units.h
@@ -2479,12 +2479,22 @@ namespace units
 		static const double PI = 3.14159265358979323846264338327950288419716939937510;
 
 		static const unit_t<unit<std::ratio<1>, dimensionless::scalar, std::ratio<1>>>														pi(1.0);									///< Ratio of a circle's circumference to its diameter.
-		static const unit_t<compound_unit<unit<std::ratio<299792458>, length::meters>, inverse<time::seconds>>>								c(1.0);										///< Speed of light in vacuum.
+		static const velocity::meters_per_second_t																							c(299792458.0);								///< Speed of light in vacuum.
 		static const unit_t<compound_unit<cubed<length::meters>, inverse<mass::kilogram>, inverse<squared<time::seconds>>>>					G(6.67408e-11);								///< Newtonian constant of gravitation.
 		static const unit_t<compound_unit<energy::joule, time::seconds>>																	h(6.626070040e-34);							///< Planck constant.
-		static const unit_t<unit<std::ratio<4, 10000000>, compound_unit<force::newton, inverse<squared<current::ampere>>>, std::ratio<1>>>	mu0(1.0);									///< vacuum permeability.
-		static const auto																													epsilon0 = 1.0 / (mu0 * units::pow<2>(c));	///< vacuum permitivity.
-
+		static const unit_t<compound_unit<force::newtons, inverse<squared<current::ampere>>>>												mu0(4.0e-7 * PI);							///< vacuum permeability.
+		static const unit_t<compound_unit<capacitance::farad, inverse<length::meter>>>														epsilon0(1.0 / (mu0 * units::pow<2>(c)));	///< vacuum permitivity.
+		static const impedance::ohm_t																										Z0(mu0 * c);								///< characteristic impedance of vacuum.
+		static 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 const charge::coulomb_t																										e(1.602176565e-19);							///< elementary charge.
+		static const mass::kilogram_t																										m_e(9.10938291e-31);						///< electron mass.
+		static const mass::kilogram_t																										m_p(1.672621777e-27);						///< proton mass.
+		static const unit_t<compound_unit<energy::joules, inverse<magnetic_field_strength::tesla>>>											mu_B(e * h / (4 * pi *m_e));				///< Bohr magneton.
+		static const unit_t<inverse<substance::mol>>																						N_A(6.02214129e23);							///< Avagadro's Number.
+		static const unit_t<compound_unit<energy::joules, inverse<temperature::kelvin>, inverse<substance::moles>>>							R(8.3144621);								///< Gas constant.
+		static const unit_t<compound_unit<energy::joules, inverse<temperature::kelvin>>>													k_B(R / N_A);								///< Boltzmann constant.
+		static const unit_t<compound_unit<charge::coulomb, inverse<substance::mol>>>														F(N_A * e);									///< Faraday constnat.
+		static const unit_t<compound_unit<power::watts, inverse<area::square_meters>, inverse<squared<squared<temperature::kelvin>>>>>		sigma((2 * pow<5>(pi) * pow<4>(R)) / (15 * pow<3>(h) * pow<2>(c) * pow<4>(N_A)));	///< Stefan-Boltzmann constant.
 	}
 
 };	// end namespace units
diff --git a/unitTests/main.cpp b/unitTests/main.cpp
index 4bca0616..be7624b9 100644
--- a/unitTests/main.cpp
+++ b/unitTests/main.cpp
@@ -1380,22 +1380,35 @@ TEST_F(UnitTest, concentrationConversion)
 
 TEST_F(UnitTest, testConstants)
 {
-	EXPECT_NEAR(299792458, meters_per_second_t(constants::c)(), 5.0e-9);
+	// scalar constants
 	EXPECT_NEAR(3.14159, constants::pi, 5.0e-6);
-//	EXPECT_NEAR(6.67408e-11, constants::G, 5.0e-17);
-//	EXPECT_NEAR(6.626070040e-34, constants::h, 5.0e-44);
-//	EXPECT_NEAR(8.854e-12, unit_t<>(constants::epsilon0()), 5.0e-15);
+
+	// constants with units
+	EXPECT_NEAR(299792458, constants::c(), 5.0e-9);
+	EXPECT_NEAR(6.67408e-11, constants::G(), 5.0e-17);
+	EXPECT_NEAR(6.626070040e-34, constants::h(), 5.0e-44);
+	EXPECT_NEAR(1.256637061e-6, constants::mu0(), 5.0e-16);
+	EXPECT_NEAR(8.854187817e-12, constants::epsilon0(), 5.0e-21);
+	EXPECT_NEAR(376.73031346177, constants::Z0(), 5.0e-12);
+	EXPECT_NEAR(8.987551787e9, constants::k_e(), 5.0e-1);
+	EXPECT_NEAR(1.602176565e-19, constants::e(), 5.0e-29);
+	EXPECT_NEAR(9.10938291e-31, constants::m_e(), 5.0e-40);
+	EXPECT_NEAR(1.672621777e-27, constants::m_p(), 5.0e-37);
+	EXPECT_NEAR(9.27400968e-24, constants::mu_B(), 5.0e-30);
+	EXPECT_NEAR(6.02214129e23, constants::N_A(), 5.0e14);
+	EXPECT_NEAR(8.3144621, constants::R(), 5.0e-8);
+	EXPECT_NEAR(1.3806488e-23, constants::k_B(), 5.0e-31);
+	EXPECT_NEAR(96485.3365, constants::F(), 5.0e-5);
+	EXPECT_NEAR(5.670373e-8, constants::sigma(), 5.0e-14);
 }
 
 TEST_F(UnitTest, radarRangeEquation)
 {
-	using Boltzmann = unit_t<compound_unit<watts, inverse<hertz>, inverse<kelvin>>>;
 
 	watt_t			P_t;				// transmit power
 	scalar_t		G;					// gain
 	meter_t			lambda;				// wavelength
 	square_meter_t	sigma;				// radar cross section
-	const Boltzmann	k(1.38e-23);		// Boltzmann constant
 	meter_t			R;					// range
 	kelvin_t		T_s;				// system noise temp
 	hertz_t			B_n;				// bandwidth
@@ -1411,7 +1424,7 @@ TEST_F(UnitTest, radarRangeEquation)
 	L = dB_t(8.0);
 
 	scalar_t SNR =	(P_t * units::pow<2>(G) * units::pow<2>(lambda) * sigma) / 
-					(units::pow<3>(4 * constants::pi) * units::pow<4>(R) * k * T_s * B_n * L);
+					(units::pow<3>(4 * constants::pi) * units::pow<4>(R) * constants::k_B * T_s * B_n * L);
 
 	EXPECT_NEAR(1.535, SNR(), 5.0e-4);
 }