Professor Paul D Smith Department of Mathematics, Division of Information and Communication Sciences, Macquarie University Analytical-numerical methods in scattering and diffraction. Wednesday 12th October 14:05-14:55pm, Carslaw Building Room 373. Numerical techniques for Maxwell's equations or the Helmholtz equation often encounter difficulties of accuracy and convergence with scattering structures that feature cavities and sharp edges, and are of moderate or large size (in wavelengths). The conversion to an equivalent integral equation formulation usually does little to ameliorate the difficulty. For cavities of spherical and other canonical shapes, an analytical process of regularisation may be used to transform the basic equations to a second kind Fredholm matrix equation; standard numerical techniques for its solution are easily applicable and scattered field results may then be computed reliably and accurately. This talk explains the basis of the technique and describes some of the structures which have been treated in this manner. Although mainly scattering problems are considered, the adaption of the method to propagation studies for waveguides will be mentioned.