From a65dbf27d9519585056632b45e8d57f2fe814667 Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Tue, 29 Jan 2019 23:53:20 -0800
Subject: [PATCH] Changed implementation of angle_between

---
 manimlib/utils/space_ops.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/manimlib/utils/space_ops.py b/manimlib/utils/space_ops.py
index 50efb097..959fd198 100644
--- a/manimlib/utils/space_ops.py
+++ b/manimlib/utils/space_ops.py
@@ -142,9 +142,8 @@ def angle_between_vectors(v1, v2):
     Returns the angle between two 3D vectors.
     This angle will always be btw 0 and TAU/2.
     """
-    l1 = get_norm(v1)
-    l2 = get_norm(v2)
-    return np.arccos(np.dot(v1, v2) / (l1 * l2))
+    diff = (angle_of_vector(v1) - angle_of_vector(v2)) % TAU
+    return min(diff, TAU - diff)
 
 
 def project_along_vector(point, vector):