Merge pull request #337 from crystal-growth/add_magnetic_permeability

Add MagneticPermeability quantity with related units.

src/si/magnetic_permeability.rs

@@ -0,0 +1,50 @@
+//! Magnetic permeability (base unit henry per meter, m · kg · s⁻² · A⁻²).
+
+quantity! {
+    /// Magnetic permeability (base unit henry per meter, m · kg · s⁻² · A⁻²).
+    quantity: MagneticPermeability; "magnetic permeability";
+    /// Dimension of magnetic permeability, LMT⁻²I⁻² (base unit henry per meter,
+    /// m · kg · s⁻² · A⁻²).
+    dimension: ISQ<
+        P1,     // length
+        P1,     // mass
+        N2,     // time
+        N2,     // electric current
+        Z0,     // thermodynamic temperature
+        Z0,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @henry_per_meter: prefix!(none); "H/m", "henry per meter", "henrys per meter";
+        @vacuum_magnetic_permeability: 1.256_637_062_12_E-6; "µ₀", "vacuum magnetic permeability",
+            "vacuum magnetic permeability";
+    }
+}
+
+#[cfg(test)]
+mod test {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::inductance as ind;
+        use crate::si::magnetic_permeability as mp;
+        use crate::si::length as l;
+        use crate::si::quantities::*;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: MagneticPermeability<V> = Inductance::new::<ind::henry>(V::one())
+                / Length::new::<l::meter>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<mp::henry_per_meter, ind::henry, l::meter>();
+
+            fn test<MP: mp::Conversion<V>, IND: ind::Conversion<V>, L: l::Conversion<V>>() {
+                Test::assert_approx_eq(&MagneticPermeability::new::<MP>(V::one()),
+                    &(Inductance::new::<IND>(V::one())
+                        / Length::new::<L>(V::one())));
+            }
+        }
+    }
+}

src/si/mod.rs

@@ -83,6 +83,7 @@ system! {
         luminous_intensity::LuminousIntensity,
         magnetic_flux::MagneticFlux,
         magnetic_flux_density::MagneticFluxDensity,
+        magnetic_permeability::MagneticPermeability,
         mass::Mass,
         mass_concentration::MassConcentration,
         mass_density::MassDensity,