Visual physics and mathematics/Chua system

The Chua system is a system of three ordinary differential equations (Differential equations, dynamical systems and an introduction to chaos, Hirsch, Morris William., Smale, Stephen, Devaney, Robert Luke, 2004):

  • dx/dt = a(y - x3/16 + x/6)
  • dy/dt = x - y + z
  • dz/dt = -by

For example b=28 and a =15.4

It is a deterministic three-dimensional flow:


All trajectories converge towards an attractor:

It is a strange attractor because it is chaotic. A moving point circulates on the 8 in a way that seems disordered: a few turns on the left part of the 8 then a few turns on the right part and so on, but the number of turns on each part is unpredictable.


A zoom on the Chua attractor:


The attractor varies depending on the parameter a: