A NOTE ON MULTIPLE RECIPROCITY INTEGRAL FORMULATION FOR THE HELMHOLTZ-EQUATION

The multiple reciprocity method (MRM) is known as a method for elimination of domain integrals appearing in the integral equation in the framework of the direct-type boundary-element formulation. The method employs the fundamental solution of a part of the adjoint operator corresponding to the original differential equation. In this paper we discuss the relation between the conventional integral equation formulation of the Helmholtz equation and that derived by means of the MRM formulation. The latter, formulated in terms of real-valued variables, is proved to be a special case of the general complex-valued formulation.