The PML in frequency domain boundary integral equations: An unexpected application

Progress in science is usually an almost continuous process only taking small steps at a time. The invention of the PML [1] by J.-P. Bérenge definitely was not continuous. The impact of this invention on computational electromagnetics and beyond cannot be overestimated. This was immediately clear for the audience that in 1994 attended the dedicated lecture at the IEEE Antennas and Propagation Symposium in Seattle. A short conversation of the first author with Bérenger several years later in Paris revealed that for J.-P. Bérenger this invention was a simple and obvious solution to a problem on his desk. He needed something that absorbed without reflection incident waves that arrived from almost any direction and for all frequencies.