Potential of the current law vs Newton
Radius of the selected particle
Units: GM = 1, reference radius 1. Acceleration a = r-n[1 + αe-r/λ(1 + r/λ)] (power law of d-1 space dimensions plus a Yukawa fifth force), leapfrog integrator with adaptive step. Precession is measured between successive periapses. Bertrand's theorem: only n = 2 closes every bound orbit.