From 6f9cccfebdd40fa91012e424c306398909aaf12f Mon Sep 17 00:00:00 2001
From: Philipp Rehner <prehner@ethz.ch>
Date: Sat, 18 Apr 2026 18:29:33 +0200
Subject: [PATCH] Extend methods of `Angle` to dual numbers

---
 CHANGELOG.md |  2 ++
 Cargo.toml   |  3 +++
 src/lib.rs   | 64 +++++++++++++++++++++++++++++++---------------------
 3 files changed, 43 insertions(+), 26 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b3c36cb..889afb4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- Added implementations for trigonometric funtions for `Angle<T>` with `T: DualNum<f64>` when the `num-dual` feature is active. [#105](https://github.com/itt-ustutt/quantity/pull/105)
 
 ## [0.13.0] - 2026-01-06
 ### Changed
diff --git a/Cargo.toml b/Cargo.toml
index f8dd49e..a519acf 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -35,6 +35,9 @@ pyo3 = { version = "0.27", optional = true }
 numpy = { version = "0.27", optional = true }
 num-dual = { version = "0.13", optional = true }
 
+[dev-dependencies]
+approx = "0.5"
+
 [features]
 default = []
 ## Use generalized (hyper-)dual numbers from the [num-dual] crate as value of a quantity.
diff --git a/src/lib.rs b/src/lib.rs
index 78f03ee..a1b2373 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -647,34 +647,46 @@ pub const RADIANS: Angle = Quantity(1.0, PhantomData);
 /// Angle unit degrees $\\left(1°=\\frac{\\pi}{180}\text{rad}\\right)$
 pub const DEGREES: Angle = Quantity(std::f64::consts::PI / 180., PhantomData);
 
-impl Angle {
-    pub fn sin(self) -> f64 {
-        self.0.sin()
-    }
-
-    pub fn cos(self) -> f64 {
-        self.0.cos()
-    }
-
-    pub fn tan(self) -> f64 {
-        self.0.tan()
-    }
-
-    pub fn asin(x: f64) -> Self {
-        Quantity(x.asin(), PhantomData)
-    }
-
-    pub fn acos(x: f64) -> Self {
-        Quantity(x.acos(), PhantomData)
-    }
+macro_rules! angle_methods {
+    ($t:ty) => {
+        pub fn sin(self) -> $t {
+            self.0.sin()
+        }
+
+        pub fn cos(self) -> $t {
+            self.0.cos()
+        }
+
+        pub fn tan(self) -> $t {
+            self.0.tan()
+        }
+
+        pub fn asin(x: $t) -> Self {
+            Quantity(x.asin(), PhantomData)
+        }
+
+        pub fn acos(x: $t) -> Self {
+            Quantity(x.acos(), PhantomData)
+        }
+
+        pub fn atan(x: $t) -> Self {
+            Quantity(x.atan(), PhantomData)
+        }
+
+        pub fn atan2(y: $t, x: $t) -> Self {
+            Quantity(y.atan2(x), PhantomData)
+        }
+    };
+}
 
-    pub fn atan(x: f64) -> Self {
-        Quantity(x.atan(), PhantomData)
-    }
+#[cfg(not(feature = "num-dual"))]
+impl Angle {
+    angle_methods!(f64);
+}
 
-    pub fn atan2(y: f64, x: f64) -> Self {
-        Quantity(y.atan2(x), PhantomData)
-    }
+#[cfg(feature = "num-dual")]
+impl<T: num_dual::DualNum<f64>> Angle<T> {
+    angle_methods!(T);
 }
 
 impl<T> Dimensionless<T> {