code: def _u0Eq(logu,delta,pot,E,Lz22):
      
      u= numpy.exp(logu)
      sinh2u= numpy.sinh(u)**2.
      cosh2u= numpy.cosh(u)**2.
      dU= cosh2u*actionAngleStaeckel.potentialStaeckel(u,numpy.pi/2.,pot,delta)
      return -(E*sinh2u-dU-Lz22/delta**2./sinh2u)
docs: The equation that needs to be minimized to find u0