@spiceErrorCheck<EOL>def prop2b(gm, pvinit, dt):
gm = ctypes.c_double(gm)<EOL>pvinit = stypes.toDoubleVector(pvinit)<EOL>dt = ctypes.c_double(dt)<EOL>pvprop = stypes.emptyDoubleVector(<NUM_LIT:6>)<EOL>libspice.prop2b_c(gm, pvinit, dt, pvprop)<EOL>return stypes.cVectorToPython(pvprop)<EOL>
Given a central mass and the state of massless body at time t_0,
this routine determines the state as predicted by a two-body
force model at time t_0 + dt.

http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/prop2b_c.html

:param gm: Gravity of the central mass.
:type gm: float
:param pvinit: Initial state from which to propagate a state.
:type pvinit: 6-Element Array of floats
:param dt: Time offset from initial state to propagate to.
:type dt: float
:return: The propagated state.
:rtype: 6-Element Array of floats