Fityk [fi:tik] is an open-source program for data processing and nonlinear curve fitting, that works for Windows, Linux and macOS.
It is primarily used:
- by scientists who analyse data from powder diffraction, chromatography, photoluminescence and photoelectron spectroscopy, infrared and Raman spectroscopy, and other experimental techniques,
- to fit peaks – bell-shaped functions (Gaussian, Lorentzian, Voigt, Pearson VII, bifurcated Gaussian, EMG, Doniach-Sunjic, etc.),
but it is suitable for fitting any curve to 2D (x,y) data.
- intuitive graphical interface (and also command line interface),
- support for many data file formats, thanks to the xylib library,
- dozens of built-in functions and support for user-defined functions,
- equality constraints,
- fitting systematic errors of the x coordinate of points (for example instrumental zero error or sample displacement correction in powder diffraction),
- manual, graphical placement of peaks and auto-placement using peak detection algorithm,
- various optimization methods (standard Marquardt least-squares algorithm, Genetic Algorithms, Nelder-Mead simplex),
- handling series of datasets,
- automation with macros (scripts) and embedded Lua for more complex scripting
- the accuracy of nonlinear regression verified with reference datasets from NIST,
- an add-on for powder diffraction data (Pawley refinement)
- modular architecture,
- open source license (GPLv2+).
- Windows: Windows 7, 8.1, and 10
- macOS: 10.6+
- Linux: Debian, Linux Mint, MX Linux, Arch Linux, Ubuntu, Fedora, and openSUSE.
- Linux Flatpak package