FFEccLawdensEqns:

--------------------------------------------------------------------------
   Compute Hills frame state given initial state, true anomaly, and eccentricity

   This method uses a closed-form solution to Lawden's equations.

   Since version 7.
--------------------------------------------------------------------------
   Form:
   xH = FFEccLawdensEqns( xH0, nu0, nu, e, n );
--------------------------------------------------------------------------

   ------
   Inputs
   ------
   xH0             (6,1)  Initial Hills frame state
   nu0              (1)   True anomaly (at initial state) [rad]
   nu              (1,n)  True anomaly (at new state) [rad]
   e                (1)   Eccentricity
   n                (1)   Mean orbit rate [rad/s] (optional)
                           * if provided, state must have time-derivatives 
                           * if NOT provided, state must have nu-derivatives 

   -------
   Outputs
   -------
   xH              (6,n)  New Hills frame state at nu (with nu-derivatives)

--------------------------------------------------------------------------
   References: Inalhan, Tillerson, How, "Relative Dynamics and Control of
   Spacecraft Formations in Eccentric Orbits", Journal of Guidance,
   Control & Dynamics, Vol.25, No.1, Jan-Feb 2002.
--------------------------------------------------------------------------
	  Copyright 2004 Princeton Satellite Systems, Inc.
   All rights reserved.
--------------------------------------------------------------------------

Children:

FormationFlying: EccDynamics/FFEccIntConst
FormationFlying: EccDynamics/FFEccRMat
FormationFlying: Utility/Nu2TimeDomain
FormationFlying: Utility/Time2NuDomain