def find_closest_trackpointLB(self,l,b,D,vlos,pmll,pmbb,interp=True,
                                   usev=False):
        """
        NAME:

           find_closest_trackpointLB

        PURPOSE:
           find the closest point on the stream track to a given point in (l,b,...) coordinates

        INPUT:

           l,b,D,vlos,pmll,pmbb- coordinates in (deg,deg,kpc,km/s,mas/yr,mas/yr)

           interp= (True) if True, return the closest index on the interpolated track

           usev= (False) if True, also use the velocity components (default is to only use the positions)

        OUTPUT:

           index of closest track point on the interpolated or not-interpolated track
           
        HISTORY:

           2013-12-17- Written - Bovy (IAS)

        """
        if interp:
            nTrackPoints= len(self._interpolatedThetasTrack)
        else:
            nTrackPoints= len(self._thetasTrack)
        if l is None:
            l= 0.
            trackL= numpy.zeros(nTrackPoints)
        elif interp:
            trackL= self._interpolatedObsTrackLB[:,0]
        else:
            trackL= self._ObsTrackLB[:,0]
        if b is None:
            b= 0.
            trackB= numpy.zeros(nTrackPoints)
        elif interp:
            trackB= self._interpolatedObsTrackLB[:,1]
        else:
            trackB= self._ObsTrackLB[:,1]
        if D is None:
            D= 1.
            trackD= numpy.ones(nTrackPoints)
        elif interp:
            trackD= self._interpolatedObsTrackLB[:,2]
        else:
            trackD= self._ObsTrackLB[:,2]
        if usev:
            if vlos is None:
                vlos= 0.
                trackVlos= numpy.zeros(nTrackPoints)
            elif interp:
                trackVlos= self._interpolatedObsTrackLB[:,3]
            else:
                trackVlos= self._ObsTrackLB[:,3]
            if pmll is None:
                pmll= 0.
                trackPmll= numpy.zeros(nTrackPoints)
            elif interp:
                trackPmll= self._interpolatedObsTrackLB[:,4]
            else:
                trackPmll= self._ObsTrackLB[:,4]
            if pmbb is None:
                pmbb= 0.
                trackPmbb= numpy.zeros(nTrackPoints)
            elif interp:
                trackPmbb= self._interpolatedObsTrackLB[:,5]
            else:
                trackPmbb= self._ObsTrackLB[:,5]
        #Calculate rectangular coordinates
        XYZ= bovy_coords.lbd_to_XYZ(l,b,D,degree=True)
        trackXYZ= bovy_coords.lbd_to_XYZ(trackL,trackB,trackD,degree=True)
        if usev:
            vxvyvz= bovy_coords.vrpmllpmbb_to_vxvyvz(vlos,pmll,pmbb,
                                                     XYZ[0],XYZ[1],XYZ[2],
                                                     XYZ=True)
            trackvxvyvz= bovy_coords.vrpmllpmbb_to_vxvyvz(trackVlos,trackPmll,
                                                          trackPmbb,
                                                          trackXYZ[:,0],
                                                          trackXYZ[:,1],
                                                          trackXYZ[:,2],
                                                          XYZ=True)
        #Calculate distance
        dist2= (XYZ[0]-trackXYZ[:,0])**2.\
            +(XYZ[1]-trackXYZ[:,1])**2.\
            +(XYZ[2]-trackXYZ[:,2])**2.
        if usev:
            dist2+= (vxvyvz[0]-trackvxvyvz[:,0])**2.\
                +(vxvyvz[1]-trackvxvyvz[:,1])**2.\
                +(vxvyvz[2]-trackvxvyvz[:,2])**2.
        return numpy.argmin(dist2)
NAME:

           find_closest_trackpointLB

        PURPOSE:
           find the closest point on the stream track to a given point in (l,b,...) coordinates

        INPUT:

           l,b,D,vlos,pmll,pmbb- coordinates in (deg,deg,kpc,km/s,mas/yr,mas/yr)

           interp= (True) if True, return the closest index on the interpolated track

           usev= (False) if True, also use the velocity components (default is to only use the positions)

        OUTPUT:

           index of closest track point on the interpolated or not-interpolated track
           
        HISTORY:

           2013-12-17- Written - Bovy (IAS)