MLFMA with local and global interpolators

Multilevel fast multipole algorithm (MLFMA) has made it possible to solve large electromagnetic problems with integral equation methods due to its good scalability in terms of both memory and CPU-time. Interpolation plays a vital role in the actual implementation of MLFMA. A good interpolator should maintain accuracy while preserving the efficiency of the algorithm. Generally speaking there are two major classes of interpolators available, local and global.