Getting the Fit parameters of a Fitted histogram

[zarpapis]

Hello, I’m trying to fit some histograms and get the fitting parameters. I want for example to make a “gaus” fit on a histogram and save the 3 fitting parameters in variables. I’m working on c++ code and the documentation for Root Browser is no good.

Could someone provide me with an example code of how I could do this or point me to a similar topic if it exists?

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ROOT Version: v5.34.38
Platform: Ubuntu 14
Compiler: g++

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[couet]

For instance you can do something like that:

$ root
   -------------------------------------------------------------------
  | Welcome to ROOT 6.15/01                       http://root.cern.ch |
  |                                      (c) 1995-2018, The ROOT Team |
  | Built for macosx64                                                |
  | From heads/master@v6-13-04-241-gc27a4eaee1, Jun 01 2018, 08:33:01 |
  | Try '.help', '.demo', '.license', '.credits', '.quit'/'.q'        |
   -------------------------------------------------------------------

root [0] TH1D *histo = new TH1D("histo", "", 100, -4, 4);
root [1] histo->FillRandom("gaus");
root [2] histo->Fit("gaus");
Info in <TCanvas::MakeDefCanvas>:  created default TCanvas with name c1
 FCN=65.0502 FROM MIGRAD    STATUS=CONVERGED      54 CALLS          55 TOTAL
                     EDM=9.21369e-07    STRATEGY= 1      ERROR MATRIX ACCURATE 
  EXT PARAMETER                                   STEP         FIRST   
  NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE 
   1  Constant     1.57425e+02   2.76819e+00   8.89596e-03  -5.39870e-04
   2  Mean         1.38321e-02   1.43799e-02   5.69927e-05   8.22303e-04
   3  Sigma        1.00178e+00   1.04857e-02   1.11224e-05  -4.31183e-01
root [3] TF1 *g = (TF1*)histo->GetListOfFunctions()->FindObject("gaus");
root [4] double c = g->GetParameter(0);
root [5] cout << c << endl;
157.425
root [6] 

It should work the same way with ROOT 5.34