Semiclassical expansion for exactly solvable differential operators

Jorge A. Borrego-Morell, Boris Shapiro

Below we study a linear differential equation $\MM (v(z,η))=η^M{v(z,η)}$, where $\eta >0$ is a large spectral parameter and $\MM=\sum_{k=1}^{M}ρ_{k}(z)\frac{d^k}{dz^k},\; M\ge 2$ is a…