Many dynamical systems in physics, chemistry and biology exhibit complex be- haviour. The apparently random motion of a fluid is the best known example. How- ever also vibrating structures, electronic oscillators, magnetic devices,lasers, chemical oscillators, and population kinetics can behave in a complicated manner. One can find irregular oscillations, which is now known as chaotic behaviour. The research field of nonlinear dynamical systems and especially the study of chaotic systems has been hailed as one of the important breaktroughs in science this century. The sim- plest realization...