def R(self,*args,**kwargs):
        """
        NAME:
           R
        PURPOSE:
           return cylindrical radius at time t
        INPUT:
           t - (optional) time at which to get the radius
           ro= (Object-wide default) physical scale for distances to use to convert
           use_physical= use to override Object-wide default for using a physical scale for output
        OUTPUT:
           R(t)
        HISTORY:
           2010-09-21 - Written - Bovy (NYU)
        """
        thiso= self(*args,**kwargs)
        onet= (len(thiso.shape) == 1)
        if onet: return thiso[0]
        else: return thiso[0,:]
NAME:
           R
        PURPOSE:
           return cylindrical radius at time t
        INPUT:
           t - (optional) time at which to get the radius
           ro= (Object-wide default) physical scale for distances to use to convert
           use_physical= use to override Object-wide default for using a physical scale for output
        OUTPUT:
           R(t)
        HISTORY:
           2010-09-21 - Written - Bovy (NYU)