question: static double computeDesiredEllipsoidMagnitude ( final PlanetModel planetModel , final double x , final double y , final double z ) { return 1.0 / Math . sqrt ( x * x * planetModel . inverseAbSquared + y * y * planetModel . inverseAbSquared + z * z * planetModel . inverseCSquared ) ; }
target:  Compute the desired magnitude of a unit vector projected to a given planet model.