source: GLBFrejus/HEAD/run/TDSyst.C@ 2

#define TDSyst_cxx
#include "TDSyst.h"
#include <TH2D.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TGraph.h>

#include <iostream>

void TDSyst::Loop()
{
//   In a ROOT session, you can do:
//      Root > .L TDSyst.C
//      Root > TDSyst t
//      Root > t.GetEntry(12); // Fill t data members with entry number 12
//      Root > t.Show();       // Show values of entry 12
//      Root > t.Show(16);     // Read and show values of entry 16
//      Root > t.Loop();       // Loop on all entries
//

//     This is the loop skeleton where:
//    jentry is the global entry number in the chain
//    ientry is the entry number in the current Tree
//  Note that the argument to GetEntry must be:
//    jentry for TChain::GetEntry
//    ientry for TTree::GetEntry and TBranch::GetEntry
//
//       To read only selected branches, Insert statements like:
// METHOD1:
//    fChain->SetBranchStatus("*",0);  // disable all branches
//    fChain->SetBranchStatus("branchname",1);  // activate branchname
// METHOD2: replace line
//    fChain->GetEntry(jentry);       //read all branches
//by  b_branchname->GetEntry(ientry); //read only this branch
   if (fChain == 0) return;

   const Double_t PI = TMath::Pi(); 


   Long64_t nentries = fChain->GetEntriesFast();

   Double_t sin2Cur = -999.;
   Double_t deltaCur = -999.;

   Int_t nbytes = 0, nb = 0;
   for (Long64_t jentry=0; jentry<nentries;jentry++) {
      Long64_t ientry = LoadTree(jentry);
      if (ientry < 0) break;
      nb = fChain->GetEntry(jentry);   nbytes += nb;
      // if (Cut(ientry) < 0) continue;
      sin2Cur = TMath::Power(TMath::Sin(2.0 * theta13),2.0);
      deltaCur= deltaCP/PI*180.0;

//       std::cout << deltaCur << " " << TMath::Log10(sin2Cur)
//              << ": chi2 " << chi2
//              << std::endl;
      histo->Fill(deltaCur,TMath::Log10(sin2Cur),chi2);
   }
}//Loop