Fitk [fi:tik] est progressio pro MGE et nonlinear curva decet.

Primo usus est

• by scientists quae notitias resolvunt ex diffractione pulveris, chromatographiae, photoluminentiae et spectroscopiae photoelectronae, infrarubri et Ramani spectroscopiae, et aliae artes experimentales;

• to fit peaks – bell-shaped functions (Gaussian, Lorentzian, Voigt, Pearson VII, bifurcated Gaussian, EMG, Doniach-Sunjic, etc.),