FFEccFrameCompare:

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   Compare two methods of computing the relative motion in an eccentric orbit.

   The first case uses the homogenous LTV solution to Lawden's equations.

   The second case computes the absolute trajectories of both orbits in
   the ECI frame, then transforms into the relative Hill's frame.

   Note: The reference elements are provided, defining one orbit. The initial
         relative state is also provided, which is added to the initial
         reference state to define the second orbit.

   Since version 7.
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   Form:
   [xH1,xH2] = FFEccFrameCompare( elRef0, xH0, nOrbits, nS, method );
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   ------
   Inputs
   ------
   elRef0          (1,6)  Initial elements of reference orbit
   xH0             (6,1)  Initial state in Hills frame
   nOrbits          (1)   Number of orbits to simulate
   nS               (1)   Number of samples to use
   method           (1)   Indicate which method to use for initialization
                             0 - do not enforce periodic motion, use supplied xH0 exactly 
                             1 - enforce periodic, symmetric motion about origin
                             2 - enforce periodic motion via fuel optimization
                             3 - enforce periodic motion using the velocity constraint
                                 (only change y-velocity)

   -------
   Outputs
   -------
   xH1             (6,nS) Relative state trajectory from first case
   xH2             (6,nS) Relative state trajectory from second case

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   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.
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	  Copyright 2004 Princeton Satellite Systems, Inc.
   All rights reserved.
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Children:

FormationFlying: EccDynamics/FFEccDMatPeriodic
FormationFlying: EccDynamics/FFEccLawdensEqns
FormationFlying: EccDynamics/FFEccRMat
FormationFlying: Transformation/ECI2Hills
FormationFlying: Transformation/Hills2ECI
Orbit: OrbitMechanics/RVOrbGen
OrbitMiniToolbox: Support/El2RV
OrbitMiniToolbox: Support/M2Nu
SC: BasicOrbit/OrbRate
SC: BasicOrbit/Period
SC: BasicOrbit/RV2El