  The Voigt profile is important for spectroscopy, astrophysics, and many other
fields of physics, but is notoriously difficult to compute. McLean et al. [J.
Electron Spectrosc. & Relat. Phenom., 1994] have proposed an approximation
using a sum of Lorentzians. Our assessment indicates that this algorithm has
significant errors for small arguments. After a brief survey of the
requirements for spectroscopy we give a short list of both efficient and
accurate codes and recommend implementations based on rational approximations.
