electronics: Add electrical impedance

electronics/src/electrical_impedance.rs

@@ -0,0 +1,44 @@
+// Copyright (c) 2023 Xu Shaohua <shaohua@biofan.org>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+//! Electrical impedance is the measure of the opposition that a
+//! circuit presents to a current when a voltage is applied.
+//!
+//! Impedance extends the concept of resistance to alternating current (AC) circuits.
+//! [Electrical impedance](https://en.wikipedia.org/wiki/Electrical_impedance)
+
+#[must_use]
+pub fn get_resistance(reactance: f64, impedance: f64) -> f64 {
+    impedance.mul_add(impedance, -reactance.powi(2)).sqrt()
+}
+
+#[must_use]
+pub fn get_reactance(resistance: f64, impedance: f64) -> f64 {
+    impedance.mul_add(impedance, -resistance.powi(2)).sqrt()
+}
+
+#[must_use]
+pub fn get_impedance(resistance: f64, reactance: f64) -> f64 {
+    resistance.hypot(reactance)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{get_impedance, get_reactance, get_resistance};
+
+    #[test]
+    fn test_get_resistance() {
+        assert_eq!(get_resistance(4.0, 5.0), 3.0);
+    }
+
+    #[test]
+    fn test_get_reactance() {
+        assert_eq!(get_reactance(4.0, 5.0), 3.0);
+    }
+
+    #[test]
+    fn test_get_impedance() {
+        assert_eq!(get_impedance(3.0, 4.0), 5.0);
+    }
+}

electronics/src/lib.rs

@@ -13,4 +13,5 @@
 //pub mod apparent_power;
 pub mod builtin_voltage;
 pub mod electric_power;
+pub mod electrical_impedance;
 pub mod ohms_law;