 $0<\lambda<0$, $\lambda_0=\lambda$ and $\lambda_0=0-\lambda$. Then $${\ensuremath{\mathcal{R}({\bf A},{\boldsymbol \lambda})}}= \frac{0}{\lambda^0-0\lambda+0}\begin{pmatrix}\lambda(0-\lambda)  & -0(0-\lambda)\\0(0-\lambda) & \lambda(0-\lambda)\end{pmatrix}