Phase Portraits and Stability

We see that the phase-plane is broken up into a sequence of fixed points and a series of both open and closed constant-energy curves. The origin (0= =0) and its periodic equivalents (0 27rn, = 0), are stable fixed points (or elliptic 

Nesting of KAM-tori For two-degree-of-freedom system, the KAM theorem states that for sufficiently weak perturbations, all sufficiently irrational KAM-tori are pre- 

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