- example: $x_{n+1} = \cos x_n$
- $x^$ is linearly stable if $|\lambda| = |f’(x^)| < 1$
- $x^$ is linearly unstable if $|\lambda| = |f’(x^)| > 1$
- $|\lambda| = |f’(x^*)| = 1$ is a marginal case → need higher order to detect local stability (or try cobweb)
- $\lambda = 0$ is super stable fixed point