def rguiding(self,*args,**kwargs):
        """
        NAME:

           rguiding

        PURPOSE:

           calculate the guiding-center radius (the radius of a circular orbit with the same angular momentum)

        INPUT:

           pot= potential instance or list of such instances

           ro= (Object-wide default) physical scale for distances to use to convert (can be Quantity)

           vo= (Object-wide default) physical scale for velocities to use to convert (can be Quantity)

           use_physical= use to override Object-wide default for using a physical scale for output

        OUTPUT:

           R_guiding

        HISTORY:

           2018-08-29 - Written as thin wrapper around Potential.rl - Bovy (UofT)

        """
        pot= kwargs.get('pot',self._orb.__dict__.get('_pot',None))
        if pot is None:
            raise RuntimeError("You need to specify the potential as pot= to compute the guiding-center radius")
        flatten_potential(pot)
        if _isNonAxi(pot):
            raise RuntimeError('Potential given to rguiding is non-axisymmetric, but rguiding requires an axisymmetric potential')
        _check_consistent_units(self,pot)
        Lz= self.Lz(*args,use_physical=False)
        return nu.array([rl(pot,lz,use_physical=False) for lz in Lz])