#include "TStyle.h"
#include "TTimer.h"
#include "Riostream.h"
#include "TCanvas.h"
#include "TGraph.h"
#include "TROOT.h"
#include "TGraphErrors.h"
#include "TFrame.h"
#include "TAxis.h"
#include "TH1F.h"
#include "TRandom.h"
#include "TF1.h"


//Breit-Wigner function
Double_t mybw(Double_t* x, Double_t* par)
{
  Double_t arg1 = 14.0/22.0; // 2 over pi
  Double_t arg2 = par[1]*par[1]*par[2]*par[2]; //Gamma=par[1]  M=par[2]
  Double_t arg3 = ((x[0]*x[0]) - (par[2]*par[2]))*((x[0]*x[0]) - (par[2]*par[2]));
  Double_t arg4 = x[0]*x[0]*x[0]*x[0]*((par[1]*par[1])/(par[2]*par[2]));
  return par[0]*arg1*arg2/(arg3 + arg4);
}

//--------------------------------------------

void hsum2(){
  gROOT->Reset();

  TCanvas * c1 = new TCanvas("c1","The HSUM example",200,10,600,400);
  c1->Divide(1,2);
  c1->cd(1);

  // Create some histograms.
  
  TH1F * main   = new TH1F("main","Main contributor",100,1382.-10.*36.,1382.+10.*36.);

  // Fill histograms randomly
  gRandom->SetSeed();
  Float_t xs1;
  for ( Int_t i=0; i<10000; i++) {
    xs1   = gRandom->BreitWigner(1382.0, 36.0);
    main->Fill(xs1);
  }
  //  main->Draw(); // to redraw axis hidden by the fill area
  main->DrawCopy(); // to redraw axis hidden by the fill area
  c1->Modified();
  c1->Update();
  //}
  c1->cd(2);
  TH1F * norm = (TH1F *) main->Clone("norm");
  norm->Scale(1./norm->Integral());
  norm->DrawCopy();


  // FIT EXERCISE

  TCanvas * cFit = new TCanvas("cFit","The Fit example",1000,500);
  cFit->Divide(2,1);
  cFit->cd(1);

  TH1F *hFit1 = (TH1F*)main->Clone("hFit1");
  hFit1->Fit("landau","R","",1340,1420);
  hFit1->DrawCopy("same");

  cFit->cd(2);

  TF1 *fBW = new TF1("fBW",mybw,1100,1700,3);
  fBW->SetParameter(0,1400);
  fBW->SetParameter(1,50);
  fBW->SetParameter(2,1500);

  TH1F *hFit2 = (TH1F*)main->Clone("hFit2");
  hFit2->Fit(fBW,"R","",1100,1700);
  hFit2->DrawCopy("same");
}