def _phiforce(self,R,phi=0.,t=0.):
        """
        NAME:
           _phiforce
        PURPOSE:
           evaluate the azimuthal force
        INPUT:
           R
           phi
           t
        OUTPUT:
          F_phi(R(,\phi,t))
        HISTORY:
           2016-06-02 - Written - Bovy (UofT)
        """
        return self._Pot.phiforce(R,0.,phi=phi,t=t,use_physical=False)
def _phiforce ( self , R , phi = 0. , t = 0. ) : return self . _Pot . phiforce ( R , 0. , phi = phi , t = t , use_physical = False )
NAME:
           _phiforce
        PURPOSE:
           evaluate the azimuthal force
        INPUT:
           R
           phi
           t
        OUTPUT:
          F_phi(R(,\phi,t))
        HISTORY:
           2016-06-02 - Written - Bovy (UofT)