\[\frac{{\mathrm{d}}^{2}u}{{\mathrm{d}\zeta}^{2}}=-\frac{\alpha\cosh u}{2(\sinh u%
)^{3}}-\frac{\beta\sinh u}{2(\cosh u)^{3}}-\tfrac{1}{4}\gamma e^{\zeta}\sinh%
\left(2u\right)-\tfrac{1}{8}\delta e^{2\zeta}\sinh\left(4u\right).\]