ROOT   Reference Guide
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Fit Tutorials

These tutorials illustrate the main fitting features. Their names are related to the aspect which is treated in the code.

## Files

file  combinedFit.C

Combined (simultaneous) fit of two histogram with separate functions and some common parameters

file  combinedFit.py

Combined (simultaneous) fit of two histogram with separate functions and some common parameters

file  ConfidenceIntervals.C

Illustrates TVirtualFitter::GetConfidenceIntervals This method computes confidence intervals for the fitted function

file  ErrorIntegral.C

Estimate the error in the integral of a fitted function taking into account the errors in the parameters resulting from the fit.

file  exampleFit3D.C

example of fitting a 3D function Typical multidimensional parametric regression where the predictor depends on 3 variables

file  fit1.C

Simple fitting example (1-d histogram with an interpreted function)

file  fit2.C

Fitting a 2-D histogram This tutorial illustrates :

file  fit2a.C

Fitting a 2-D histogram (a variant) This tutorial illustrates :

file  fit2d.C

Example illustrating how to fit a 2-d histogram of type y=f(x)

file  fit2dHist.C

file  fitCircle.C

Generate points distributed with some errors around a circle Fit a circle through the points and draw To run the script, do, eg

file  fitcont.C

Example illustrating how to draw the n-sigma contour of a Minuit fit.

file  fitConvolution.C

Tutorial for convolution of two functions

file  fitConvolution.py

Tutorial for convolution of two functions

file  fitExclude.C

Illustrates how to fit excluding points in a given range.

file  fithist.C

Example of fit where the model is histogram + function

file  fitLinear.C

Example of fitting with a linear function, using TLinearFitter This example is for a TGraphErrors, but it can also be used when fitting a histogram, a TGraph2D or a TMultiGraph

file  fitLinear2.C

Fit a 5d hyperplane by n points, using the linear fitter directly

file  fitLinearRobust.C

This tutorial shows how the least trimmed squares regression, included in the TLinearFitter class, can be used for fitting in cases when the data contains outliers.

file  fitMultiGraph.C

fitting a parabola to a multigraph of 3 partly overlapping graphs with different errors

file  fitNormSum.C

Tutorial for normalized sum of two functions Here: a background exponential and a crystalball function Parameters can be set:

file  fitNormSum.py

Tutorial for normalized sum of two functions Here: a background exponential and a crystalball function Parameters can be set:

file  fitpanel_playback.C
This file will test all the transient frames (aka Dialog windows) displayed in the fitpanel, as the rest of the functionality is tried automatically with the UnitTest.C unit.

file  fitslicesy.C

Illustrates how to use the TH1::FitSlicesY function It uses the TH2F histogram generated in macro hsimple.C It invokes FitSlicesY and draw the fitted "mean" and "sigma" in 2 sepate pads.

file  FittingDemo.C

Example for fitting signal/background.

file  graph2dfit.C

Fitting a TGraph2D

file  Ifit.C

Example of a program to fit non-equidistant data points

file  langaus.C

Convoluted Landau and Gaussian Fitting Function (using ROOT's Landau and Gauss functions)

file  line3Dfit.C

Fitting of a TGraph2D with a 3D straight line

file  minuit2FitBench.C

Demonstrate performance and usage of Minuit2 and Fumili2 for monodimensional fits.

file  minuit2FitBench2D.C

file  minuit2GausFit.C

Perform fits with different configurations using Minuit2

file  multidimfit.C

Multi-Dimensional Parametrisation and Fitting

file  multifit.C

Fitting multiple functions to different ranges of a 1-D histogram Example showing how to fit in a sub-range of an histogram A histogram is created and filled with the bin contents and errors defined in the table below.

file  multifit.py

Fitting multiple functions to different ranges of a 1-D histogram Example showing how to fit in a sub-range of an histogram A histogram is created and filled with the bin contents and errors defined in the table below.

file  myfit.C

Get in memory an histogram from a root file and fit a user defined function.

file  NumericalMinimization.C

Example on how to use the new Minimizer class in ROOT Show usage with all the possible minimizers.

file  qa2.C

Test generation of random numbers distributed according to a function defined by the user

file  TestBinomial.C

Perform a fit to a set of data with binomial errors like those derived from the division of two histograms.

file  TwoHistoFit2D.C

Example to fit two histograms at the same time.

file  vectorizedFit.C

Tutorial for creating a Vectorized TF1 function using a formula expression and use it for fitting an histogram