> * Reader for nbody_sh1p a parallel direct N-body code*    Educational N-body integrator with a shared but variable time step    (the same for all particles but changing in time), using the Hermite    integration scheme (Hut, P. & Makino, M, 2003    <http://www.artcompsci.org> in /The art of Computer Science/). The    source code has been adapted for a parallel ring algorithm using the    MPI <www-unix.mcs.anl.gov/mpi/mpich/> library.        download latest source code of nbody_sh1p.tar.gz        <nbody_sh1p.tar.gz>     nbody_sh1p.tar.gz contains the following files:    README This file    Makefile Makefile (requires MPI)    nbody_sh1p.C The main parallel N-body code.    pipe.C Routines to circulate data around in a ring. This is all    reasonably standard MPI In fact, it is standard MPE, but repeated    here for consistency and independence (original version of pipe.C    <http://wotug.ukc.ac.uk/parallel/standards/mpi>)    pipe.h Header file for pipe.C    n24body.in An example input file for a 24-particle system    n24body.out Output for the example input file (run on a single    processor).    Typical command line (generates : n24body.out)    *%* nbody_sh1p < n24body.in > n24body.out    28 November 2003    Simon Portegies Zwart    Version log:        Version 1.0: Initial development by Put & Makino on 1 Jan 2002        Version 2.0: Adopted for MPI by Portegies Zwart on 2 Okt 2003         Version 2.01: Bug fix and independent Makefile 	              by Portegies Zwart on 25 Jun 2004    > *Initial performance and timing analysis.*    MPI N-body timing <./timing.jpg>        Small timing test (perfomed by A. Gualandris) for 128, 256 and        512 particles with up to 32 processors on the Blue (Boewulf)        linux cluster at SARA <http://www.sara.nl>.        These tests were run for 10 N-body time units for a Plummer        model and a King model with W_0 = 12