Add magnetic H field with related units.

src/si/magnetic_field_strength.rs

@@ -0,0 +1,58 @@
+//! Magnetic field strength (H field) (base unit ampere per meter, m⁻¹ · A).
+
+quantity! {
+    /// Magnetic field strength (H field) (base unit ampere per meter, m⁻¹ · A).
+    quantity: MagneticFieldStrength; "magnetic field strength (H field)";
+    /// Dimension of magnetic field strength (H field), L⁻¹I (base unit ampere per meter, m⁻¹ · A).
+    dimension: ISQ<
+        N1,     // length
+        Z0,     // mass
+        Z0,     // time
+        P1,     // electric current
+        Z0,     // thermodynamic temperature
+        Z0,     // amount of substance
+        Z0>;    // luminous intensity
+    units {
+        @ampere_per_meter: prefix!(none); "A/m", "ampere per meter", "amperes per meter";
+        @ampere_per_centimeter: prefix!(none) / prefix!(centi); "A/cm", "ampere per centimeter",
+            "amperes per centimeter";
+        @ampere_per_millimeter: prefix!(none) / prefix!(milli); "A/mm", "ampere per millimeter",
+            "amperes per millimeter";
+        @ampere_per_micrometer: prefix!(none) / prefix!(micro); "A/μm", "ampere per micrometer",
+            "amperes per micrometer";
+
+        /// 1 oersted = 1000/(4π) A/m
+        @oersted: 79.577_471_545_947_67; "Oe", "oersted", "oersteds";
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    storage_types! {
+        use crate::num::One;
+        use crate::si::length as l;
+        use crate::si::electric_current as i;
+        use crate::si::magnetic_field_strength as h;
+        use crate::si::quantities::*;
+        use crate::tests::Test;
+
+        #[test]
+        fn check_dimension() {
+            let _: MagneticFieldStrength<V> = ElectricCurrent::new::<i::ampere>(V::one())
+                / Length::new::<l::meter>(V::one());
+        }
+
+        #[test]
+        fn check_units() {
+            test::<i::ampere, l::meter, h::ampere_per_meter>();
+            test::<i::ampere, l::centimeter, h::ampere_per_centimeter>();
+            test::<i::ampere, l::millimeter, h::ampere_per_millimeter>();
+            test::<i::ampere, l::micrometer, h::ampere_per_micrometer>();
+
+            fn test<I: i::Conversion<V>, L: l::Conversion<V>, H: h::Conversion<V>>() {
+                Test::assert_approx_eq(&MagneticFieldStrength::new::<H>(V::one()),
+                    &(ElectricCurrent::new::<I>(V::one()) / Length::new::<L>(V::one())));
+            }
+        }
+    }
+}

src/si/mod.rs

@@ -81,6 +81,7 @@ system! {
         length::Length,
         luminance::Luminance,
         luminous_intensity::LuminousIntensity,
+        magnetic_field_strength::MagneticFieldStrength,
         magnetic_flux::MagneticFlux,
         magnetic_flux_density::MagneticFluxDensity,
         mass::Mass,