Unstable Periodic Orbits in the Stadium Billiard
  A systematic numerical technique for the calculation of unstable periodic orbits in the stadium billiard is presented. All the periodic orbits up to order $p=11$ are calculated and then used to calculate the average Lyapunov exponent and the topological entropy. Applications to semiclassical quantization and to experiments in mesoscopic systems and microwave cavities are noted. 
Ofer Biham and Mark Kvale