#define invm_cxx
#include "invm.h"
#include "TH2.h"
#include "TStyle.h"
#include "TCanvas.h"
#include <iostream>
#include "TCanvas.h"   //<===========================
using namespace std;
#include "TMatrixD.h"

void invm::Loop()
{// invm loop starts 
  
  Double_t PI    = 3.1428571428571 ; cout << "  PI  " << PI << endl;
  Double_t twoPI = 2*PI ; cout << "  twoPI  " << twoPI << endl;


  /////  Defining Histogram Array.....  ///////////////
  TH1F *Dca[8];
  Dca[0] = new TH1F("Dca_0","dca distribution: no correction:-40<z<-30",24000,-1.2,1.2);
  Dca[1] = new TH1F("Dca_1","dca distribution: no correction:-30<z<-20",24000,-1.2,1.2);
  Dca[2] = new TH1F("Dca_2","dca distribution: no correction:-20<z<-10",24000,-1.2,1.2);
  Dca[3] = new TH1F("Dca_3","dca distribution: no correction:-10<z<0",24000,-1.2,1.2);
  Dca[4] = new TH1F("Dca_4","dca distribution: no correction:0<z<10",24000,-1.2,1.2);
  Dca[5] = new TH1F("Dca_5","dca distribution: no correction:10<z<20",24000,-1.2,1.2);
  Dca[6] = new TH1F("Dca_6","dca distribution: no correction:20<z<30",24000,-1.2,1.2);
  Dca[7] = new TH1F("Dca_7","dca distribution: no correction:30<z<40",24000,-1.2,1.2);

  Double_t Sigdca  [8] = {0.0},         Errsigdca[8] = {0.0};         
  Double_t Chisq_1a[8] = {0.0},         Ndf_1a   [8] = {0.0};

  Double_t zbin[9]={0.0} 
  for(Int_t i=0;i<9;i++)zbin[i]=-40.0+(i*10.0); 
  
  Double_t dca = 0.0,   phi = 0.0 ;

  if (fChain == 0) return;
  Int_t nentries = Int_t(fChain->GetEntries()); Int_t nbytes = 0; Int_t nb = 0;

  //////////////   Event loop start here
  for(Int_t ev=0 ; ev < nentries ; ev++ )
    {//first  event loop start with   ev = 0  
      if(LoadTree(ev) < 0) break;  nb = fChain->GetEntry(ev); nbytes += nb;
      if(ev%100==0)cout<<ev<<"  event is proccesing  " << endl;      
      for(Int_t l=0; l<Gtr401atDCA_ntrk401DCA; l++)
        {//gtr401 event loop 
	  
	  dca = Gtr401atDCA_par0[l]; ///dca value       
          phi = Gtr401atDCA_par2[l];  /// phi value
	  if(Gtr401atDCA_par2[l]<0.0)phi = 2*PI + Gtr401atDCA_par2[l];
	  Double_t zval = Gtr401atDCA_par1[l]; /// z value
	      
	  for(Int_t i=0; i<8; i++)
	    { // if z value is lying in specific z bin
	      if(zval>zbin[i] && zval<zbin[i+1])Dca[i]->Fill(dca);// here filling histogram  
	    }
	}
    }
 
  
  ////////  *******   PROBLEM PART   *****************
  /////////////////////////////////
  ///////    defining variables  for    fitting
  Double_t chisq=0.0, ndf=0.0 ;
  Double_t sigma=0.0,     errsigma=0.0;  
  
  for(Int_t i=0; i<8; i++)
    { // here i am doing fitting 
      gausfit(Dca[i],sigma,errsigma,chisq,ndf);
      Sigdca  [i] = sigma ;         Errsigdca[i] = errsigma ;         
      Chisq_1a[i] = chisq;          Ndf_1a[i] = ndf ;
    } // it works of first histogram, then it fails 
  //after first fitting  it gives following error message
  //---------------------------------------------------------
  //<TCanvas::MakeDefCanvas>: created default TCanvas with name c1
  //  *** Break *** segmentation violation
  //  Root > Function gausfit() busy flag cleared
  //  Function Loop() busy flag cleared
  //---------------------------------------------------------
  ///////  ***************************************************



  ////////////////////
  ///////////////       writing histogram in file
  TFile *out = new TFile("example_avd.root","RECREATE");
  out->Clear();
  ////////////  set line color of histo
  Dca_0->SetLineColor(3);
  Dca_1->SetLineColor(3);
  Dca_2->SetLineColor(3);
  Dca_3->SetLineColor(3);
  Dca_4->SetLineColor(3);
  Dca_5->SetLineColor(3);
  Dca_6->SetLineColor(3);
  Dca_7->SetLineColor(3);

  //////////////////   write histo on root file
  Dca_0->Write();
  Dca_1->Write();
  Dca_2->Write();
  Dca_3->Write();
  Dca_4->Write();
  Dca_5->Write();
  Dca_6->Write();
  Dca_7->Write();
  out->Close(); 
}