def test_euler_instability():
# Test for numerical errors in mat2euler
# problems arise for cos(y) near 0
po2 = pi / 2
zyx = po2, po2, po2
M = nea.euler2mat(*zyx)
# Round trip
M_back = nea.euler2mat(*nea.mat2euler(M))
yield assert_true, np.allclose(M, M_back)
# disturb matrix slightly
M_e = M - FLOAT_EPS
# round trip to test - OK
M_e_back = nea.euler2mat(*nea.mat2euler(M_e))
yield assert_true, np.allclose(M_e, M_e_back)
# not so with crude routine
M_e_back = nea.euler2mat(*crude_mat2euler(M_e))
yield assert_false, np.allclose(M_e, M_e_back)
def test_euler_mat():
M = nea.euler2mat()
yield assert_array_equal, M, np.eye(3)
for x, y, z in eg_rots:
M1 = nea.euler2mat(z, y, x)
M2 = sympy_euler(z, y, x)
yield assert_array_almost_equal, M1, M2
M3 = np.dot(x_only(x), np.dot(y_only(y), z_only(z)))
yield assert_array_almost_equal, M1, M3
zp, yp, xp = nea.mat2euler(M1)
# The parameters may not be the same as input, but they give the
# same rotation matrix
M4 = nea.euler2mat(zp, yp, xp)
yield assert_array_almost_equal, M1, M4