My apologies, I misunderstood the meaning of "simulation". I was thinking of a calculation where you compute the interactions between objects and evolve their p

My apologies, I misunderstood the meaning of "simulation". I was thinking of a calculation where you compute the interactions between objects and evolve their positions and momenta accordingly. Celestia does not do this of course, it uses some time series where the coefficients are computed in advance. For these purposes using fixed point and/or integer arithmetic instead of floating points could be entirely appropriate, I do not know enough to form a preference.