##

Duffing's oscillator

The Duffing's equation is described by this nonlinear differential equation :

where and are parameters and a pulsation.

This forced oscillator should be written as a three dimensional state equation system :

Te = 0.02
g = 0.3
a = 0.15
w = 1
To = 2*%pi/w
ci1 = 0.1
ci2 = 0.1
ci3 = 0
Tfin = 400

**Figure :** (a) Phase plan

**Figure :** (b) Time domain waveforms

**Figure :** (c) Poincare section

A. Layec