Contents Part I Periodic Behavior 1 Dynamics Hall of Fame 3 1. Basic Concepts of Dynamics 13 1.1 State spaces 15 1.2 Dynamical systems 21 1.3 Special trajectories 30 1.4 Asymptotic approach to limit sets 36 1.5 Attractors, basins, and separatrices 42 1.6 Gradient systems 47 2. Classical Applications: Limit Points in 2D from Newton to Rayleigh 53 2.1 Pendula 55 2.2 Buckling columns 65 2.3 Percussion instruments 71 2.4 Predators and prey 82 3. Vibrations: Limit Cycles in 2D from Rayleigh to Rashevsky 87 3.1 Wind instruments 89 3.2 Bowed instruments 94 3.3 Radio transmitters 103 3.4 Biological morphogenesis 106 4. Forced Vibrations: Limit Cycles in 3D from Rayleigh to Duffing 113 4.1 The ring model for forced springs 115 4.2 Forced linear springs 126 4.3 Forced hard springs 139 4.4 Harmonics 148vi Contents 5. Compound Oscillations: Invariant Tori in 3D from Huyghens to Hayashi 159 5.1 The torus model for two oscillators 161 5.2 The torus model for coupled oscillators 167 5.3 The ring model for forced oscillators 172 5.4 Braids: the dynamics of entrainment 176 5.5 Response curves for frequency changes 185 5.6 Forced electric oscillators 192 Conclusion 199