Efficient Application of the Voigt Functions in the Fourier Transform

In this work, we develop a method of rational approximation of the Fourier transform (FT) based on the real and imaginary parts of the complex error function \[ w(z) = e^{-z^2}(1 - {\rm{erf}}(-iz)) = K(x,y) + iL(x,y), \quad z = x + iy, \] where $K(x,y)$ and $L(x,y)$ are known as the Voigt and imaginary Voigt functions, respectively. In contrast to our previous rational approximation of the FT, the expansion coefficients in this method are not dependent on values of a sampled function. As a set of the Voigt/complex error function values remains the same, this approach provides rapid computation. Mathematica codes with some examples are presented.