Example3.cxx

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// $Id$
//-----------------------------------------------------------------------
//       The GSI Online Offline Object Oriented (Go4) Project
//         Experiment Data Processing at EE department, GSI
//-----------------------------------------------------------------------
// Copyright (C) 2000- GSI Helmholtzzentrum fuer Schwerionenforschung GmbH
//                     Planckstr. 1, 64291 Darmstadt, Germany
// Contact:            http://go4.gsi.de
//-----------------------------------------------------------------------
// This software can be used under the license agreements as stated
// in Go4License.txt file which is part of the distribution.
//-----------------------------------------------------------------------

 
#ifndef __CINT__
 
#include <iostream>
 
#include "TH1.h"
#include "TFile.h"
#include "TApplication.h"
 
#include "TGo4Fitter.h"
#include "TGo4FitModelFunction.h"
 
void Example3();
 
int main(int argc, char **argv)
{
   TApplication theApp("Application", nullptr, nullptr);
 
   Example3();
 
   theApp.Run();
 
   return 0;
}
 
extern "C" Double_t gaussian_(Double_t *axis, Double_t *pars);
 
// routine to read histogram from examples file
TH1D* GetHistogram(const char *HistogramName)
{
   TFile *f = TFile::Open("histograms.root");
   if (!f) return nullptr;
   TH1D *histo = nullptr;
   f->GetObject(HistogramName, histo);
   if (histo) histo->SetDirectory(nullptr);
   delete f;
   return histo;
}
 
void Example3()
{
// create fitter, select fit function and add standard actions list
   TGo4Fitter fitter("Fitter", TGo4Fitter::ff_ML_Poisson, kTRUE);
 
// add histogram to fitter, which should be fitted
   fitter.AddH1("data1", GetHistogram("hDeg120_P_c"), kTRUE, 2200., 2900.);
 
// create polynom of first order
   fitter.AddPolynomX( "data1", "Pol", 1);
 
// create model, which uses user function to calculate gaussian shape
   fitter.AddModel("data1", new TGo4FitModelFunction("Gauss1", &gaussian_, 2, kTRUE));
   fitter.AddModel("data1", new TGo4FitModelFunction("Gauss2", &gaussian_, 2, kTRUE));
 
// set initial values of user model parameters
   fitter.SetParValue("Gauss1.Par0",2553.);
   fitter.SetParValue("Gauss1.Par1",15.);
   fitter.SetParValue("Gauss2.Par0",2672.);
   fitter.SetParValue("Gauss2.Par1",15.);
 
// add output actions
   fitter.AddOutputAction("Draw","#data1,Gauss1,Gauss2");
   fitter.AddOutputAction("Print","Pars");
 
// perform all actions
   fitter.DoActions();
}
 
#else
 
void Example3()
{
   std::cout << "This example uses linked FORTRAN library," << std::endl;
   std::cout << "therefore it can not be run in CINT" << std::endl;
}
 
#endif