fix (#66)

Cargo.toml

@@ -26,6 +26,7 @@ num-traits = "0.2"
 typenum = "1.17"
 pyo3 = { version = "0.22", optional = true }
 numpy = { version = "0.22", optional = true }
+num-dual = { version = "0.10", optional = true }
 
 [features]
 default = []

src/lib.rs

@@ -443,6 +443,15 @@ impl<T, U> Quantity<T, U> {
     {
         &self.0 / unit.0
     }
+
+    /// Convert a quantity into the given unit and return it
+    /// as a float or array.
+    pub fn convert_into<T2>(self, unit: Quantity<T2, U>) -> Quot<T, T2>
+    where
+        T: Div<T2>,
+    {
+        self.0 / unit.0
+    }
 }
 
 impl<U> Zero for Quantity<f64, U> {
@@ -454,3 +463,15 @@ impl<U> Zero for Quantity<f64, U> {
         self.0.is_zero()
     }
 }
+
+#[cfg(feature = "num-dual")]
+mod num_dual {
+    use super::Quantity;
+    use num_dual::DualNum;
+
+    impl<D: DualNum<f64>, U> Quantity<D, U> {
+        pub fn re(&self) -> Quantity<f64, U> {
+            Quantity::new(self.0.re())
+        }
+    }
+}