[itishappy]

Oops, pretty big mistake on my part. I gave the formula for force and labeled it acceleration. Way too late to edit, but the correctly labeled formulas should have been:

    F = G * m1 * m2 / |r|^2 * r_unit
    F = G * m1 * m2 / |r|^3 * r

Or as acceleration, by dividing out an `m` using `F=ma`:

    a = G * m / |r|^2 * r_unit
    a = G * m / |r|^3 * r