I have a question here, in order to have a stable solution of a differential equation, is that right we should have all eigenvalues less one?
But I have seen a incomprehensible situation in difference equation, for instance
\begin{align*} x_{t+1}&=a x_{t} -b y_t\\ y_t&= y_{t+1}-cx_{t+1} \end{align*} $a$, $b$ and $c$ are parameters, there are two eignenvalues, one has to be less than one, the other has to be larger than one in order to keep system stable. I completely do not grasp this idea. If anyone knows, please explain to me! Thanks!