Algorithm 810: The SLEIGN2 Sturm-Liouville code

The SLEIGN2 code is based on the ideas and methods of the original SLEIGN c ode of 1979. The main purpose of the SLEIGN2 code is to compute eigenvalues and eigenfunctions of regular and singular self-adjoint Sturm-Liouville pr oblems, with both separated and coupled boundary conditions, and to approxi mate the continuous spectrum in the singular case. The code uses some new a lgorithms, which we describe, and has a driver program that offers a user-f riendly interface. In this paper the algorithms and their implementation ar e discussed, and the class of problems to which each algorithm applies is i dentified.