Equation 5.20.96C8BC3AC251D

\begin{equation} |v|^2_{h_ x}= \left\{ \begin{aligned} 0,& \quad \textup{if }v=0;\\ |v|^2_{h_{0,x}}\mathrm{e}^{-\varphi (x)},& \quad \textup{if }v\neq 0. \end{aligned} \right. \end{equation}