Perfectly matched layer

Summary

A perfectly matched layer (PML) is an artificial absorbing layer placed around a computational domain to simulate waves that leave to infinity. Waves enter the layer without any reflection, at every angle and frequency, and then decay exponentially inside it. It was introduced by Bérenger in 1994 for Maxwell's equations, and it is now understood as an analytic continuation of space to complex coordinates. It is used with the finite-difference time-domain method, the finite element method and other methods for wave equations.