Absorption spectral line GSA for N = 10, 20, and 30 Gaussian functions. Top row (a): comparison of various GSA for an absorption line, employing different numbers of Gaussian functions in the approximation process. The blue solid line represents the synthetic profile, and the red dotted line represents the best GSA of 200 MC simulations. Bottom row (b): difference between the synthetic profiles and GSA. The blue solid line represents the difference between the synthetic profile and the best GSA.