Poincaré map 876732 216838496 2008-06-03T13:23:43Z RussBot 279219 Robot-assisted fix [[WP:DPL|links to disambiguation page]] Function In [[mathematics]], particularly in [[dynamical systems]], a '''first recurrence map''' or '''Poincaré map''', named after [[Henri Poincaré]], is the intersection of a [[periodic orbit]] in the [[state space]] of a [[continuous dynamical system]] with a certain lower dimensional subspace, called the '''Poincaré section''', [[Transversality|transversal]] to the [[Flow (mathematics)|flow]] of the system. More precisely, one considers a periodic orbit with initial conditions on the Poincaré section and observes the point at which this orbits first returns to the section, thus the name first recurrence map. The transversality of the Poincaré section basically means that periodic orbits starting on the subspace flow through it and not parallel to it. A Poincaré map can be interpreted as [[discrete dynamical system]]s with a state space that is one dimension smaller than the original continuous dynamical system. Because it preserves many properties of periodic and quasiperiodic orbits of the original system and has a lower dimensional state space it is often used for analyzing the original system. In practise this is not always possible as there is no general method to construct a Poincaré map. A Poincaré map differs from a [[recurrence plot]] in that space, not time, determines when to plot a point. For instance, the locus of the moon when the earth is at [[perihelion]] is a recurrence plot; the locus of the moon when it passes through the plane perpendicular to the earth's orbit and passing through the sun and the earth at perihelion is a Poincaré map. It was used by [[Michel Hénon]] to study the motion of stars in a [[galaxy]], because the path of a star projected onto a plane looks like a tangled mess, while the Poincaré map shows the structure more clearly. == Definition == [[Image:Poincare map.svg|thumb|230px|In Poincaré section ''S'', the Poincaré map ''P'' projects point ''x'' onto point ''P(x)''.]] Let ('''R''', ''M'', &phi;) be a [[global dynamical system]], with '''R''' the [[real number]]s, ''M'' the [[phase space]] and &phi; the [[evolution function]]. Let &gamma; be a [[periodic orbit]] through a point ''p'' and ''S'' be a local differentiable and transversal section of &phi; through ''p'', called '''Poincaré section''' through ''p''. Given an open and connected [[neighbourhood (mathematics)|neighbourhood]] ''U'' of ''p'', a [[Function (mathematics)|function]] :<math>P: U \to S</math> is called '''Poincaré map''' for orbit &gamma; on the '''Poincaré section''' ''S'' through point ''p'' if * ''P''(''p'') = ''p'' * ''P''(''U'') is a neighbourhood of ''p'' and ''P'':''U'' &rarr; ''P''(''U'') is a [[diffeomorphism]] * for every point ''x'' in ''U'', the [[positive semi-orbit]] of ''x'' intersects ''S'' for the first time at ''P''(''x'') == Poincaré maps and stability analysis == Poincaré maps can be interpreted as a [[discrete dynamical system]]. The [[stability theory|stability]] of a periodic orbit of the original system is closely related to the stability of the fixed point of the corresponding Poincaré map. Let ('''R''', ''M'', &phi;) be a [[differentiable dynamical system]] with periodic orbit &gamma; through ''p''. Let :<math>P: U \to S</math> be the corresponding Poincaré map through ''p''. We define :<math>P^0 := id_U</math> :<math>P^{n+1} := P \circ P^n</math> :<math>P^{-n-1} := P^{-1} \circ P^{-n}</math> and :<math>P(n, x) := P^{n}(x)</math> then ('''Z''', ''U'', ''P'') is a discrete dynamical system with state space ''U'' and evolution function :<math>P: \mathbb{Z} \times U \to U.</math> Per definition this system has a fixed point at ''p''. The periodic orbit &gamma; of the continuous dynamical system is [[Stability_theory|stable]] if and only if the fixed point ''p'' of the discrete dynamical system is stable. The periodic orbit &gamma; of the continuous dynamical system is [[asymptotically stable]] if and only if the fixed point ''p'' of the discrete dynamical system is asymptotically stable. == See also == * [[Poincaré recurrence]] * [[Stroboscopic map]] * [[Hénon map]] * [[Recurrence plot]] == References == * Nicholas B. TUFILLARO, ''[http://www.drchaos.net/drchaos/Book/node101.html Poincaré Map]'', (1997) * Shivakumar JOLAD, ''[http://www.personal.psu.edu/users/s/a/saj169/Poincaremap/Htmlfiles/PoincareMapintro.html Poincare Map and its application to 'Spinning Magnet' problem]'', (2005) [[Category:Dynamical systems]] {{Mathapplied-stub}} [[de:Poincaré-Abbildung]] [[es:Aplicación de Poincaré]] [[hu:Poincaré-féle követőfüggvény]] [[nl:Poincaré-afbeelding]]