Perturbation technique for matrix equations and its application in the computation of internal fields in a three-dimensional arbitrarily shaped biological body

A novel matrix perturbation technique for the matrix equation [A][u]=[b] is presented. One of its applications, the computation of internal fields in a three-dimensional arbitrarily shaped heterogeneous biological body illuminated by a plane wave, is further investigated by using the technique. If one regards a normal biological body as the primary model and stores its computation results, when small perturbations in the dielectric characteristics or the shape of the body occur, the internal fields in the perturbed biological body can be rapidly computed using the stored results. Compared with the usual moment methods, the new technique has an equivalent precision, yet takes only 1/70 the execution time. This technique is especially suitable for pathological cases in which the dielectric characteristics or the shape of the biological body vary due to disease