Canonical coordinates (I, θ) on an integrable system in which the Hamiltonian depends only on the actions I: dθ/dt = ∂H/∂I = ω(I), dI/dt = 0. The actions are period integrals; the angles linearise the flow on invariant tori.
Canonical coordinates (I, θ) on an integrable system in which the Hamiltonian depends only on the actions I: dθ/dt = ∂H/∂I = ω(I), dI/dt = 0. The actions are period integrals; the angles linearise the flow on invariant tori.