Fityk

Fityk 1.0.1 under Windows
Developer(s)	Marcin Wojdyr
Initial release	2004; 20 years ago (2004)
Stable release	1.3.1 / 19 December 2016; 7 years ago (2016-12-19)
Repository	github.com/wojdyr/fityk
Written in	C++
Operating system	Cross-platform
Type	Curve fitting
License	GNU GPL
Website	fityk.nieto.pl

Fityk is curve fitting and data analysis application, predominantly used to fit analytical, bell-shaped functions to experimental data. It is positioned to fill the gap between general plotting software and programs specific for one field, e.g. crystallography or XPS.^[1]

Originally, Fityk was developed to analyse powder diffraction data. It is also used in other fields that require peak analysis and peak-fitting, like chromatography or various kinds of spectroscopy.^[2]

Fityk is free and open source, distributed under the terms of GNU General Public License, with binaries/installers available free of charge on the project's website. It runs on Linux, macOS, Microsoft Windows, FreeBSD and other platforms. It operates either as a command line program or with a graphical user interface.

It is written in C++, using wxWidgets, and providing bindings for Python and other scripting languages.

Features

• three weighted least squares methods:
  • Levenberg-Marquardt algorithm,
  • Nelder-Mead method
  • Genetic algorithm
• about 20 built-in functions and support for user-defined functions
• equality constraints
• data manipulations,
• handling series of datasets,
• automation of common tasks with scripts.

Alternatives

The programs LabPlot, MagicPlot and peak-o-mat have similar scope.

More generic data analysis programs with spread-sheet capabilities include the proprietary Origin and its clones QtiPlot (paid, closed source) and SciDAVis (non-paid, open source).