A global approximation method for second-kind nonlinear integral equations

TL;DR

This paper introduces a global Nyström-type approximation method for solving nonlinear second-kind integral equations, demonstrating stability, convergence, and effectiveness through numerical tests and an application to nonlinear boundary conditions.

Contribution

It develops a unified Nyström method for both smooth and weakly singular kernels, with proven stability and convergence, and applies it to nonlinear boundary value problems.

Findings

Method shows good numerical performance

Convergence and stability are theoretically established

Applicable to nonlinear boundary problems

Abstract

A global approximation method of Nystr\"om type is explored for the numerical solution of a class of nonlinear integral equations of the second kind. The cases of smooth and weakly singular kernels are both considered. In the first occurrence, the method uses a Gauss-Legendre rule whereas in the second one resorts to a product rule based on Legendre nodes. Stability and convergence are proved in functional spaces equipped with the uniform norm and several numerical tests are given to show the good performance of the proposed method. An application to the interior Neumann problem for the Laplace equation with nonlinear boundary conditions is also considered.