%0 Journal Article %T A Simple Formulation of the Fast Multipole Method: Pseudo-Particle Multipole Method %A Atsushi Kawai %A Junichiro Makino %J Physics %D 1998 %I arXiv %X We present the pseudo-particle multipole method (P2M2), a new method to handle multipole expansion in fast multipole method and treecode. This method uses a small number of pseudo-particles to express multipole expansion. With this method, the implementation of FMM and treecode with high-order multipole terms is greatly simplified. We applied P2M2 to treecode and combined it with special-purpose computer GRAPE. Extensive tests on the accuracy and calculation cost demonstrate that the new method is quite attractive. %U http://arxiv.org/abs/astro-ph/9812431v1