Fitter

The AIDA IFitter interface provides the user the possibility to fit IFunctions to any AIDA data storage object. Binned fits can be perfomed on IHistograms, IProfiles and IDataPointSets, while unbinned fits can be performed on IClouds and ITuples. Simple fits can be perfomed directely on the data storage objects while the IFitData interface is to be used for a greater control over the data, in particular its ranges and the connection to the IFunction's variables. Through the IFitter it is also possible to change the underlying optimization engine as well as the fit method used.

Chi2 Fit to an IHistogram

A simple chi2 fit to an histogram is perfomed in the example below:

Simple Binned and Unbinned Fits

In the example below it is shown how to perfom a binned and an unbinned fit over the same data using different optimizers and fit methods.

In the JAIDA implementation there are currently two optimizers available: Minuit and Uncmin and it is possible to choose among the following fit methods: ChiSquared, CleverChiSquared, BinnedMaximumLikelihood, LeastSquares, UnbinnedMaximumLikelihood.

Control fit parameters and set constraints

With the IFitter interface it is possible to have a more direct control over the fit: the parameters in the fit can be controlled with the IFitParameterSettings interface and it is also possible to set constraints among them. In the example below we create a scripted function an show how to control its parameters:

Scans and contours

Scans and contours can be obtained as shown below:


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