The asymptotic form of the solution of an elliptic equation with the singularly perturbed boundary condition (Q1903994)

The complete asymptotic expansion of the solution of the singularly perturbed elliptic equation in \(\Omega\subset \mathbb{R}^2\) \[ \varepsilon^2 \Delta u- k^2 u=0, \qquad -\varepsilon^\alpha {{\partial u} \over {\partial n}}+ hu= \varphi \quad \text{on } \partial\Omega \] is constructed.