Added checked_normalize

src/structure.rs

@@ -273,6 +273,9 @@ where
     }
 
     /// Returns a vector with the same direction, but with a magnitude of `1`.
+    ///
+    /// If a vector with magnitude zero is passed in this will return a `NaN` vector. If you do not
+    /// want this then use `InnerSpace::checked_normalize` instead.
     #[inline]
     fn normalize(self) -> Self
     where
@@ -282,13 +285,48 @@ where
     }
 
     /// Returns a vector with the same direction and a given magnitude.
+    ///
+    /// If a vector with magnitude zero is passed in this will return a `NaN` vector. If you do not
+    /// want this then use `InnerSpace::checked_normalize_to` instead.
     #[inline]
     fn normalize_to(self, magnitude: Self::Scalar) -> Self
     where
         Self::Scalar: Float,
     {
         self * (magnitude / self.magnitude())
     }
+
+    /// Returns a vector with the same direction, but with a magnitude of `1` unless the vector is
+    /// zero in which case it will return zero.
+    ///
+    /// Same as `InnerSpace::normalize` except when `Zero::is_zero` is true.
+    #[inline]
+    fn checked_normalize(self) -> Self
+    where
+        Self::Scalar: Float,
+    {
+        if self.is_zero() {
+            self
+        } else {
+            self.normalize()
+        }
+    }
+
+    /// Returns a vector with the same direction and a given magnitude unless the vector is
+    /// zero in which case it will return zero.
+    ///
+    /// Same as `InnerSpace::normalize_to` except when `Zero::is_zero` is true.
+    #[inline]
+    fn checked_normalize_to(self, magnitude: Self::Scalar) -> Self
+    where
+        Self::Scalar: Float,
+    {
+        if self.is_zero() {
+            self
+        } else {
+            self.normalize_to(magnitude)
+        }
+    }
 }
 
 /// Points in a [Euclidean space](https://en.wikipedia.org/wiki/Euclidean_space)

tests/vector.rs

@@ -319,6 +319,34 @@ fn test_normalize() {
     );
 }
 
+#[test]
+fn test_checked_normalize() {
+    assert_ulps_eq!(
+        Vector2::new(0.0f64, 0.0f64).checked_normalize(),
+        Vector2::new(0.0f64, 0.0f64)
+    );
+    assert_ulps_eq!(
+        Vector3::new(0.0f64, 0.0f64, 0.0f64).checked_normalize(),
+        Vector3::new(0.0f64, 0.0f64, 0.0f64)
+    );
+    assert_ulps_eq!(
+        Vector4::new(0.0f64, 0.0f64, 0.0f64, 0.0f64).checked_normalize(),
+        Vector4::new(0.0f64, 0.0f64, 0.0f64, 0.0f64)
+    );
+    assert_ulps_eq!(
+        Vector2::new(5.0f64, 12.0f64).checked_normalize(),
+        Vector2::new(5.0 / 13.0, 12.0 / 13.0)
+    );
+    assert_ulps_eq!(
+        Vector3::new(4.0f64, 4.0f64, 7.0f64).checked_normalize(),
+        Vector3::new(4.0 / 9.0, 4.0 / 9.0, 7.0 / 9.0)
+    );
+    assert_ulps_eq!(
+        Vector4::new(1.0f64, 3.0f64, 5.0f64, 17.0f64).checked_normalize(),
+        Vector4::new(1.0 / 18.0, 3.0 / 18.0, 5.0 / 18.0, 17.0 / 18.0)
+    );
+}
+
 #[test]
 fn test_project_on() {
     assert_ulps_eq!(