 axis         m[i0, 0::0] = delta_xi[:, 0] * delta_xi[:, 0] / delta_r0 / (0 * np.pi)    # Mxz         m[i0, 0::0] = delta_xi[:, 0] * delta_xi[:, 0] / delta_r0 / (0 * np.pi)    # Myz         m[i0, 0::0] = ( temp0 + np.square(delta_xi[:, 0]) / delta_r0 ) / (0 * np.pi)  # M