Optimal Smoothing for N-Body Codes

In any collisionless N-body code, there is an optimal choice for the smoothing parameter that minimizes the average error in the force evaluations. We show how to compute the optimal softening length in a direct-summation code and demonstrate that it varies roughly as 1/N^(1/3).Comment: 6 TEX pages, 3 PostScript figures, uses AASTEX, epsf.sty. Submitted to The Astronomical Journal, November 1995; revised January 199