from calcephpy import *
peph = CalcephBin.open("example1.dat")
AU = peph.getconstant("AU")
jd0 = 2451542
dt = 0.5
PV = peph.compute_unit(jd0, dt, NaifId.MOON, NaifId.EARTH,
Constants.UNIT_KM+Constants.UNIT_SEC+Constants.USE_NAIFID)
print(PV)
peph.close()