AP3M: Adaptive Particle-particle, Particle-mesh Code
Abstract: AP3M is an adaptive particle-particle, particle-mesh code. It is older than Hydra but faster and more memory-efficient for dark-matter only calculations. The Adaptive P3M technique (AP3M) is built around the standard P3M algorithm. AP3M produces fully equivalent forces to P3M but represents a more efficient implementation of the force splitting idea of P3M. The AP3M program may be used in any of the three modes with an appropriate choice of input parameter.
Credit: Hugh Couchman, Frazer Pearce, Peter Thomas