def METHOD_NAME(ph_nacl: Phonopy):
    """Test of force constants calculation with fcsym by NaCl."""
    fc_1_10 = ph_nacl.force_constants[1, 10]
    # print("".join(["%f, " % v for v in fc_1_10.ravel()]))
    np.testing.assert_allclose(fc_1_10.ravel(), fc_1_10_ref, atol=1e-5)