testUserFunc.cxx

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// @(#)root/minuit2:$Id: testUserFunc.cxx 20880 2007-11-19 11:23:41Z rdm $
// Author: L. Moneta    10/2005  

/**********************************************************************
 *                                                                    *
 * Copyright (c) 2005 ROOT Foundation,  CERN/PH-SFT                   *
 *                                                                    *
 **********************************************************************/


#include "TApplication.h"
#include "TH1.h"
#include "TF1.h"
#include "TRandom3.h"
#include "TVirtualFitter.h"
#include "TMath.h"

#include <iostream>

double myfunc( double * x, double * p) { 

  return p[0]*TMath::Gaus(x[0],p[1],p[2]);
}

void testUserFunc(std::string type="Minuit2", int n = 1000) { 



  gRandom = new TRandom3();


  TVirtualFitter::SetDefaultFitter(type.c_str() );

  

  TH1D * h1 = new TH1D("h1","fit histo 1",100, -5, 5. );

//   gStyle->SetOptStat(1111111);
//   gStyle->SetOptFit(1111111);

 
    

  for (int i = 0; i < n; ++i) { 
    h1->Fill( gRandom->Gaus(0,1) ); 
  }
 
  TF1 * f = new TF1("f",myfunc,-10,10,3);
  double p[3] = { 100.0, 0.0, 1.0 } ;
  f->SetParameters(p);
  
  h1->Fit(f); 
  // try fix a parameter 
  //TVirtualFitter * fitter = TVirtualFitter::GetFitter(); 
  //std::cout << typeid(*fitter).name() << std::endl; 
  //fitter->FixParameter(2); 
  f->FixParameter(2,1.0); 

  h1->Fit(f,"V");

  h1->Draw();
 


}

#ifndef __CINT__
int main(int argc, char **argv)
{
   if (argc > 1) {  
      TApplication theApp("App", &argc, argv);
      testUserFunc( );
      theApp.Run();
   }
   else 
      testUserFunc( );
   return 0;
}
#endif

//#ifndef __CINT__
//int main() { 
//  testUserFunc( );
//}
//#endif

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