Projects / Fityk


Fityk is nonlinear curve-fitting and data analysis software. It allows data visualization, separation of overlapping peaks, and least squares fitting using standard Levenberg-Marquardt algorithm, a genetic algorithm, or Nelder-Mead simplex method. It knows about many functions (mostly bell-shaped, like Gaussian, Loretzian, Pearson 7, Voigt, Pseudo-Voigt, and Doniach-Sunjic) and user-defined functions can be easily added. It also enables background subtracting, data calibration, and task automation with a simple script language. It is mainly used to analyze powder diffraction patterns, chromatography, photoluminescence, infrared, and Raman spectroscopy, but it can be used to fit analytical functions to any kind of data.

Operating Systems

Recent releases

  •  28 Apr 2014 00:11

    Release Notes: A few optimization methods from the NLopt library have been added. A sigmoid function shape has been added. Several bugs have been fixed.

    •  07 Nov 2012 00:23

      Release Notes: Lua scripting has been improved. Problems with printing on Linux have been fixed. A new dialog has been added to the GUI (Configure > Default Directories).

      •  28 May 2012 03:00

        Release Notes: This release adds C, Ruby, and Java binding to the libfityk library and enhances the Lua and Python API. A new fitting method has been added, an implementation of the Levenberg-Marquard algorithm which uses the MPFIT library.

        •  29 Sep 2011 23:40

          Release Notes: A few minor bugs have been fixed. One new dialog (Model-Export Formula) has been added to the GUI.

          •  19 Jul 2011 14:00

            Release Notes: A Lua interpreter has been embedded in the program. It is possible to subtract a background stored in another file now. Support for mouse wheel and extra buttons has been added. All reported bugs have been fixed.


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