def test_check_screw_axis():
random_state = np.random.RandomState(73)
omega = norm_vector(random_vector(random_state, 3))
v = random_vector(random_state, 3)
assert_raises_regexp(ValueError, "Expected 3D vector with shape",
check_screw_axis, np.r_[0, 1, v])
assert_raises_regexp(ValueError,
"Norm of rotation axis must either be 0 or 1",
check_screw_axis, np.r_[2 * omega, v])
assert_raises_regexp(ValueError, "If the norm of the rotation axis is 0",
check_screw_axis, np.r_[0, 0, 0, v])
S_pure_translation = np.r_[0, 0, 0, norm_vector(v)]
S = check_screw_axis(S_pure_translation)
assert_array_almost_equal(S, S_pure_translation)
S_both = np.r_[omega, v]
S = check_screw_axis(S_both)
assert_array_almost_equal(S, S_both)
def test_random_screw_axis():
random_state = np.random.RandomState(893)
for _ in range(5):
S = random_screw_axis(random_state)
check_screw_axis(S)