Requirements of a Package for N-Body Simulations of the Solar System

N-body simulations of the Solar System form a challenging set of initial value problems for numerical integrators. The challenge comes from the variety of problems and their size – one recent simulation had 300,015 second order equations and required 9×10¹⁰ integration steps. A number of packages for specific types of simulations are available. I discuss what is required of a package intended to efficiently perform a wide range of N-body simulations.