Oscillatory Stormer-Cowell methods

摘要

We consider explicit methods for initial-value problems for special second-order ordinary differential equations where the right-hand side does not contain the derivative of y and where the solution components are known to be periodic with frequencies ω_j lying in a given nonnegative interval [ω,ω-bar]. The aim of the paper is to exploit this extra information and to modify a given integration method in such a way that the method parameters are "tuned" to the interval [ω,ω-bar]. Such an approach has already been proposed by Gautschi in 1961 for linear multistep methods for first-order differential equations in which the dominant frequencies ω_j are a priori known. In this paper, we only assume that the interval [ω,ω-bar] is known. Two "tuning" techniques, respectively based on a least squares and a minimax approximation, are considered and applied to the classical explicit Stormer-Cowell methods and the recently developed parallel explicit Stormer-Cowell methods.