duffing_oscillator

 Duffing Oscillator example (nonlinear system)

 Example taken from:
 @InProceedings { FotEtal:2006:IFA_2224,
     author={I.A. Fotiou and Ph. Rostalski and B. Sturmfels and M. Morari},
     title={{An algebraic geometry approach to nonlinear parametric
       optimization in control}},
     booktitle={American Control Conference},
     pages={},
     year={2006},
     address={},
     month=jun,
     url={http://control.ee.ethz.ch/index.cgi?page=publications;action=details;id=2224}
 }