bug fix: unnecessary equality for setting velocities to zero in  removed.
@@ -132,7 +132,7 @@ def test_case_compress_straight_rod():
# computes damping forces and forces due to stress together.
# In order to decouple these two forces. We set velocity zero.
# We will check damping forces in another test in this file.
- velocity = velocity[:] = np.array([0.0, 0.0, 0.0]).reshape(3, 1)
+ velocity[:] = np.array([0.0, 0.0, 0.0]).reshape(3, 1)
test_rod.velocity = velocity
# Internal forces in between elements have to be zero, because
