TransformGeom2Hills:

Path: FormationFlying/Transformation

% Transform geometric goals to hills-frame coordinates. 
   Works for either circular or eccentric orbits.

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   Usage:
   xH = TransformGeom2Hills( el, g, nu );
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   Inputs
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   el           (1,6)  Reference orbital elements [a,i,W,w,e,M]
   g             (.)   Geometric goals data structure
   nu            (1)   Time step for the simulation [sec] (not used)

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   Outputs
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   xH           (6,1)  Relative position and velocity in Hills frame [km; km/s]
   
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