P4M: a parallel version of P3M

We present a basic parallel version of the particle-particle/particle-mesh (P3M) code for cosmological simulations. The resulting code (P4M) uses expl icit message passing in the form of MPL and was implemented in a pioneering 1995-1997 effort on the IBM RS/6000 SP distributed-memory supercomputer. W e present tests and comparisons to the serial version. We examine performan ce issues and discuss applications and future modifications. (C) 2000 Elsev ier Science B.V. All rights reserved.