NAME:
  eccrec
 PURPOSE:   (one line only)
  Compute coordinates given eccentricy anomaly
 DESCRIPTION:
  Given elements, compute heliocentric rectangular coords,
     and heliocentric distance

  NOTE
     the epoch is implicit in the eccentric anomaly and auxiliary elements
 CATEGORY:
  Celestial Mechanics
 CALLING SEQUENCE:
  eccrec,a,ecc,eccanom,px,qx,py,qy,pz,qz,x,y,z
 INPUTS:
  a    - Semi-major axis (AU)
  ecc  - Eccentricity
  eccanom - Eccentric Anomaly (radians)
  px,qx,py,qy,pz,qz - auxilary orbital elements (equinox J2000)
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
 OUTPUTS:
  x,y,z - heliocentric equatorial rectangular coordinates (J2000, radians)
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  2002/05/29 - Marc W. Buie, Lowell Observatory.  Ported from fortran routines
    supplied by Larry Wasserman and Ted Bowell.