Status | Results of the roots of the characteristic equations of points | Fixed points |

Non-hyperbolic | ${\lambda}_{1}=1,{\lambda}_{2}=1$ | ${p}_{0}=\left(i,0\right)$ |

Non-hyperbolic | ${\lambda}_{1}=1,{\lambda}_{2}=1$ | ${p}_{1}=\left(-i,0\right)$ |