code: def normalize(self,norm,t=0.):
          
          self._amp*= norm/nu.fabs(self.Rforce(1.,0.,t=t,use_physical=False))
docs: NAME:
  
             normalize
  
          PURPOSE:
  
             normalize a potential in such a way that vc(R=1,z=0)=1., or a 
             fraction of this
  
          INPUT:
  
             norm - normalize such that Rforce(R=1,z=0) is such that it is 'norm' of the force necessary to make vc(R=1,z=0)=1 (if True, norm=1)
  
          OUTPUT:
             
             (none)
  
          HISTORY:
  
  
             2010-07-10 - Written - Bovy (NYU)