Notes: An assessment of some closed-form expressions for the Voigt function III: Combinations of the Lorentz and Gauss functions

Abstract: A variety of "pseudo-Voigt" functions, i.e. a linear combination of the Lorentz and Gauss function (occasionally augmented with a correction term), have been proposed as a closed-form approximation for the convolution of the Lorentz and Gauss function known as the Voigt function. First, a compact review of several approximations using a consistent notation is presented. The comparison with accurate reference values indicates relative errors as large as some percent.