Rational approximations to l/v/1 - s 2, one-way wave equations and absorbing boundary conditions

One-way wave equations (OWWEs), derived from rational approximations, C(s) to I/x/1 S 2, are considered. Absorbing boundary conditions obtained from these OWWEs are easily implemented, producing systems of differential equations at the boundary which are different from those produced by rational approximations, r(s) to x/1 s 2. Although these systems are different, a particular choice of difference approximation for the system yields numerical methods such that stability properties of both approaches are equivalent. In particular, for C(s) = 1/r(s), the two systems possess equivalent stability properties. In other cases, numerical results are presented which demonstrate that, where C(s) and r(s) are not derived via interpolation, the C(s) OWWEs can provide better absorption.