Path: SC/Ephem

% Simplified planet ephemerides from the almanac.
 Has functions for the orbital elements of the planets in the 
 heliocentric frame. The elements are row vectors as follows:

   a = [   a1 a0] semi-major axis
   e = [   e1 e0] eccentricity
   i = [   i1 i0] inclination
   W = [   W1 W0] longitude of the ascending node
   w = [   w1 w0] argument of perigee
   L = [L2 L1 L0] mean longitude: L2 is revolutions per century


   x = b1*T + b0 where T is Julian Centuries from J2000.0

 and bi is a coefficient. Output of the angular quantities is
 either in degrees or radians.

 If one output is specified it will be a data structure containing
 the planet information.

 Type Planets for a demo. See SolarSys for computing planet locations.

   Planets;               % demo
   planetList = Planets;  % list of planets
   [name, a, e, i, W, w, L, jDRef, mu, m, radius] = Planets( units, k )
   d = Planets( units, k )  % output a data structure array

   units           (1,3) Angular units ('deg' or 'rad')
   k         (1,1) or {} Planet IDs, if not input get all nine;
                         can be a cell array

   name            (n,:) Name of planet
   a               (n,2) Mean distance (au)
   e               (n,2) Eccentricity
   i               (n,2) Inclination wrt ecliptic plane (units)
   W               (n,2) Longitude of ascending node wrt vernal equinox (units)
   w               (n,2) Argument of perhelion (units)
   L               (n,3) Mean longitude (units)
   jDRef           (1,1) Reference Julian date
   mu              (n,2) Gravitational parameter (km^3/s^2)
   m               (n,1) Mass  (kg)
   radius          (n,1) Radius (km)
     - OR -
   d                (:)  Data structure array with above fields
                    n is the number of planets

 References:  Seidelmann, P. K., ed., Explanatory Supplement to the Astronomical
              Almanac, University Science Books, 1992.
              Table 5.8.1. p. 316.


SC: Ephem/SolarSys

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