code: def _evaluate_xyz(self,x,y,z):
          
          return 2.*numpy.pi*self._b*self._c\
              *_potInt(x,y,z,self._psi,
                       self._b2,self._c2,glx=self._glx,glw=self._glw)
docs: Evaluation of the potential as a function of (x,y,z) in the 
          aligned coordinate frame