Nodel Vector (vecn)

Not Reviewed
vecn =
MichaelBartmess.Nodel Vector (vecn)
This equation computes the Nodal Vector, vecn, which points in the direction of the orbit's ascending node -- the point where the orbit crosses the equator going from South to North.  The inputs are the x and y components of the angular momentum vector, vech.  The Nodal Vector is in the Equatorial plane.
vecZ is the unit vector in the polar direction.