BeamFit is a GUI based program to fit a Sum of Pearson functions to a one dimensional intensity distribution of an ion beam.

BeamFit requires the following to run:

• NumPy
• Matplotlib
• SciPy

To start the BeamFit GUI, clone it locally and run it with a Python 3 interpreter like so:

$ git clone https://github.com/hobler/beam-fit
$ cd beam-fit/beamfit
$ python3 beamfit_gui.py

To start working with BeamFit a measurement data file has to be loaded up either through the corresponding option under File or by pressing Ctrl + O. This file has to be a .csv file to work. After the file is loaded the parameters for the fitting can be altered on the right. In the top right the number of pearson functions can be increased or decreased. When increasing the number of functions, a new tab will appear with the parameters for the new function.

The fitting parameters can be changed in the middle section on the right side. Those parameters are the kurtoses (beta), the standard deviation (sigma) and the scalar factor (c) with which the function will be multiplied before it gets added. Their start value for the fitting can be changed by changing the value in the corresponding field of the parameter. By checking the box on the right of the parameter, the parameter gets fixed and the value in the field is now the fixed value. After changing the parameter options the fitting can be started with the "Fit" button in the bottom right corner. When the fitting is completed the fitted parameters will appear in the field below the parameter options. If needed the newly fitted parameters can be used as the new initial parameters with the "Use fitted parameters" button.

The result of the fitting can be saved in many ways. The function values can be saved through the File menu. These will be saved as a .csv file. Also, just the values of the fitted parameters can be saved via the File menu as a .csv file. The graph which is displayed on the left side can be saved through the toolbar below the graph. Furthermore, the current work-setup can be saved with the Save options option in the File menu. All the current fitting options for the parameters will be saved and can be later loaded up to continue work from the last session.

This is a brief summary of the option menus

• Load measurement data: Loads .csv file with measurement data
• Load options: Loads options file from previous session
• Save fitted function: Saves fitted function as .csv file
• Save parameters: Saves parameters as .csv file
• Save options: Saves fitting options as .json file

• Semilog: swaps between linear and semi-logarithmic representation
• Legend: turns on and off the legend
• Individual functions: Shows or hides all the individual pearson functions
• Change x values: Opens window to change the x values which are used to plot the fitted function