/* Constants for eph_lookup.  Don't casually change these, as the code
   for lookup was translated from FORTRAN and depends on these values. */
#define EPH_MERCURY  1
#define EPH_VENUS    2
#define EPH_EARTH    3
#define EPH_MARS     4
#define EPH_JUPITER  5
#define EPH_SATURN   6
#define EPH_URANUS   7
#define EPH_NEPTUNE  8
#define EPH_PLUTO    9
#define EPH_MOON    10
#define EPH_SUN     11
#define EPH_SSBARY  12 /* Solar-system barycenter */
#define EPH_EMBARY  13 /* Earth/moon barycenter */

/* eph_open opens an ephemeris, returning an opaque handle,
   which is passed to all the other functions. */
extern void *eph_open(const char *);

/* eph_close closes an open ephemeris.
   The handle goes invalid and must not be used again. */
extern void eph_close(void *);

/* eph_lookup looks up the position of `targ' relative to `cent', at the
   given date/time; it fills in a six-element output vector with X, Y, Z,
   vX, vY, vZ values (in AU and AU/day).  Arguments:
	eph_lookup(void *handle, double date, int targ, int cent, double *out)
   targ and cent are EPH_xxx constants from above.
   Return value is 0 for success, or one of the EPHL_ERR_xxx constants.
   On error, the output vector may or may not have been modified. */
extern int eph_lookup(void *, double, int, int, double *);
#define EPHL_ERR_RANGE 1 /* time value is out of range of ephemeris */