## Abstract

The numerical evaluation of surface integrals is the most
time-consuming part of the extended boundary condition method
(EBCM) for calculating the **T** matrix. An efficient
implementation of the method is presented for homogeneous particles
with discrete geometric symmetries and is applied to regular polyhedral
prisms of finite length. For such prisms, an efficient quadrature
scheme for computing the surface integrals is
developed. Exploitation of these symmetries in conjunction with the
new quadrature scheme leads to a reduction in CPU time by 3 orders of
magnitude from that of a general EBCM implementation with no
geometry-specific adaptations. The improved quadrature scheme and
the exploitation of symmetries account for, respectively, 1 and 2
orders of magnitude in the total reduction of the CPU time. Test
results for scattering by rectangular parallelepipeds and hexagonal
plates are shown to agree well with corresponding results obtained by
use of the discrete-dipole approximation. A model application for
various polyhedral prisms is presented.

© 2001 Optical Society of America

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