I need to draw the Poincarè map of a dynamical system with $ d=2$ degrees of freedom, so I have $ 4$ dynamical variables. Two of them, $ n_2$ and $ n_3$ are “actions” while the others, $ \varphi_2$ and $ \varphi_3$ are “angles”, so they are defined $ \mathrm {mod}(2\pi)$ . The four equationsRead more