A hybrid FE-FMM technique for electromagnetic scattering

The authors apply a version of the fast multipole method (FMM) to reduce the storage and computational requirement of the boundary integral in the finite-element boundary-integral method. By virtue of its O(N/sup 1.5/) operation count, the application of the single-stage FMM results in substantial speedup of the boundary-integral portion of the code, independently of the shape of the boundary-integral contour. They discuss the efficiency of the method and present an application of the technique to electromagnetic scattering from large grooves recessed in a ground plane.