Formula_9748

\[\begin{gathered}h^{2} u_{t t}+L\left(x,-i h \partial / \partial_{x}\right) u=0, \\L(x, p)=4 c^{2}(x) \sin ^{2} p / 2, x \in \mathbb{R}^{1},-\pi \leqslant p \leqslant \pi,\end{gathered}\]