1. A computer program product, used in a computer system having a processor, for modeling an electromagnetic response of an arbitrarily shaped three-dimensional object to an arbitrary time-harmonic incident field by means of a well-conditioned boundary integral equation (BIE), the computer program product comprising: a. a recording medium; b. means, recorded on the recording medium for producing a discretized representation of a well-conditioned BIE to provide a well-conditioned, finite-dimensional linear system whose solution approximates a distribution of equivalent surface sources on a model caused by the arbitrary time-harmonic incident field; and c. means, recorded on the recording medium, for solving the linear system to determine values of the equivalent surface sources; whereby solution of the well-conditioned finite-dimensional linear system provides improved computational efficiency and solution accuracy.