CableTensionExample:

--------------------------------------------------------------------------
   Cable tension example.
--------------------------------------------------------------------------
   Form:
   t = CableTensionExample( x, time, t0 )
--------------------------------------------------------------------------

   ------
   Inputs
   ------
   x               (1,3)   Nominal state [weight/unit length; length;sag]
   time            (1,1)   Not used
   t0              (1,1)   Base tension

   -------
   Outputs
   -------
   t               (1,1)   Tension

--------------------------------------------------------------------------