diff --git a/fixtracks/utils/trackingdata.py b/fixtracks/utils/trackingdata.py
index 9a8f297..8fc2808 100644
--- a/fixtracks/utils/trackingdata.py
+++ b/fixtracks/utils/trackingdata.py
@@ -175,12 +175,11 @@ class TrackingData(QObject):
             bodyaxis = [0, 1, 2, 5]
         bodycoords = self.coordinates()[:, bodyaxis, :]
         head_tail_vector = bodycoords[:, -1, :] - bodycoords[:, 0, :]
-        head_tail_length = np.linalg.norm(head_tail_vector, axis=1, keepdims=True)
-        normalized_head_tail_vector = head_tail_vector / head_tail_length
-
-        projections = np.einsum('ijk,ij->ik', bodycoords - bodycoords[:, 0, np.newaxis, :], normalized_head_tail_vector)
-        distances = np.linalg.norm(bodycoords - (bodycoords[:, 0, np.newaxis, :] + projections[:, :, np.newaxis] * normalized_head_tail_vector[:, np.newaxis, :]), axis=2)
-        deviation = np.mean(distances, axis=1)
+        head_tail_vector = head_tail_vector[:, np.newaxis ,:]  # cross-product only defined in space, not in 2D
+        head_tail_length = np.linalg.norm(head_tail_vector, axis=1, keepdims=True)  # pythagoras, length of head- tail connection
+        point_axis_vectors = bodycoords - head_tail_vector
+        deviations = np.cross(head_tail_vector, point_axis_vectors)/head_tail_length
+        deviation = np.mean(deviations, axis=1)
         return deviation
 
     def __getitem__(self, key):
@@ -237,7 +236,8 @@ def main():
     lengths = data.animalLength()
     frames = data["frame"]
     tracks = data["track"]
-    bendedness = data.bendedness()
+    
+    # bendedness = data.bendedness()
 
     embed()
     tracks = data["track"]