2.

Dependence of the variance–covariance matrix elements C _kl on the mixing parameter (η). Green circles and pink squares respectively display the values of the variance–covariance matrix elements C _kl for the Gaussian and Lorentzian profiles, calculated under the conditions I = 1000, Γ = 10, and Δx = 0.1 based on eqs and . Light blue crosses represent the numerically computed C _kl for the pseudo-Voigt profile, along with their fitted curves. Each element C _kl was obtained as the inverse of the Fisher information matrix (i.e., $\mathbb{C}={\mathbb{F}}^{-\mathbf{1}}$ ). Calculations were performed under the same conditions as those of Figure , with η of 0.001–0.999 (Table S1).