-------------------------------------------------------------------------------
   Computes the orbit right ascension angle
   given the sun unit vector (or right ascension and declination),
   the sun beta angle and the inclination of the orbit.

   Type SunRA for a demo.

-------------------------------------------------------------------------------
   Form:
   rA = SunRA( i, uSun, beta )
-------------------------------------------------------------------------------

   ------
   Inputs
   ------
   i            (1,1)  Inclination (rad)
   uSun         (3,1)  Sun Vector or [rASun (rad);decSun (rad)];
   beta         (1,n)  Beta angles (rad)

   -------
   Outputs
   -------
   rA           (1,n)  Right ascension of the ascending node (rad)

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