pub unsafe extern "C" fn jpl_pleph(
ephem: *mut c_void,
et: f64,
ntarg: c_int,
ncent: c_int,
rrd: *mut f64,
calc_velocity: c_int
) -> c_int
This subroutine reads the jpl planetary ephemeris
and gives the position and velocity of the point 'ntarg'
with respect to 'ncent'.
Calling sequence parameters:
et = (double) julian ephemeris date at which interpolation
is wanted.
ntarg = integer number of 'target' point.
ncent = integer number of center point.
The numbering convention for 'ntarg' and 'ncent' is:
1 = mercury 8 = neptune
2 = venus 9 = pluto
3 = earth 10 = moon
4 = mars 11 = sun
5 = jupiter 12 = solar-system barycenter
6 = saturn 13 = earth-moon barycenter
7 = uranus 14 = nutations (longitude and obliq)
15 = librations, if on eph. file
16 = lunar mantle omega_x,omega_y,omega_z
17 = TT-TDB, if on eph. file
(If nutations are wanted, set ntarg = 14.
For librations, set ntarg = 15. set ncent= 0.
For TT-TDB, set ntarg = 17. I've not actually
seen an ntarg = 16 case yet.)
rrd = output 6-element, double array of position and velocity
of point 'ntarg' relative to 'ncent'. The units are au and
au/day. For librations the units are radians and radians
per day. In the case of nutations the first four words of
rrd will be set to nutations and rates, having units of
radians and radians/day.
The option is available to have the units in km and km/sec.
for this, set km=TRUE at the beginning of the program.
calc_velocity = integer flag; if nonzero, velocities will be
computed, otherwise not.