code: def calcu0(self,E,Lz):
                                     
          logu0= optimize.brent(_u0Eq,
                                args=(self._delta,self._pot,
                                      E,Lz**2./2.))
          return numpy.exp(logu0)
docs: NAME:
             calcu0
          PURPOSE:
             calculate the minimum of the u potential
          INPUT:
             E - energy
             Lz - angular momentum
          OUTPUT:
             u0
          HISTORY:
             2012-11-29 - Written - Bovy (IAS)