Cosmological Simulations Using Special Purpose Computers: Implementing P3M on Grape

Abstract

An adaptation of the Particle-Particle/Particle-Mesh (P3M) code to the special purpose hardware GRAPE is presented. The short range force is calculated by a four chip GRAPE-3A board, while the rest of the calculation is performed on a Sun Sparc 10/51 workstation. The limited precision of the GRAPE hardware and algorithm constraints introduce stochastic errors of the order of a few percent in the gravitational forces. Tests of this new P3MG3A code show that it is a robust tool for cosmological simulations. The code currently achieves a peak efficiency of one third the speed of the vectorized P3M code on a Cray C-90 and significant improvements are planned in the near future. Special purpose computers like GRAPE are therefore an attractive alternative to supercomputers for numerical cosmology.Comment: 9 pages (ApJS style); uuencoded compressed PostScript file (371 kb) Also available by anonymous 'ftp' to astro.Princeton.EDU [128.112.24.45] in: summers/grape/p3mg3a.ps (668 kb) and WWW at: http://astro.Princeton.EDU/~library/prep.html (as POPe-600) Send all comments, questions, requests, etc. to: [email protected]