This equation produces the norm of the Eccentricity Vecotor, `vece`, with input being the components of the orbital radius vector, `vecr` and the components of the velocity vector, `vecv`.
The orbits and trajectories that can be characterized by eccentricity are:
elliptical: circular: e = 1 parabolic trajectory hyperbolic trajectory |
0 < e < 1 e = 1 e = 1 e> 1 |