Application of a symplectic integrator in a non-integrable relativistic   system
  We present a detailed comparison of several integration schemes applied to the dynamic system consisting of a charged particle on the Kerr background endowed with the axisymmetric electromagnetic test field. In particular, we compare the performance of the symplectic integrator with several non-symplectic routines and discuss under which circumstances we should choose the symplectic one and when we should switch to some other scheme. We are basically concerned with two crucial, yet opposing aspects - accuracy of the integration and CPU time consumption. The latter is generally less critical in our application while the highest possible accuracy is strongly demanded. 
Ond\v{r}ej Kop\'a\v{c}ek, Vladim\'ir Karas, Ji\v{r}\'i Kov\'a\v{r} and   Zden\v{e}k Stuchl\'ik
gr-qc astro-ph.HE