//#include "Riostream.h"
void basic_new3() {
//  Read data from an ascii file and create a root file with an histogram and an ntuple.
//   see a variant of this macro in basic2.C
//Author: Rene Brun

      

   gStyle->SetOptFit(1);
   
    gStyle->SetOptTitle(1);
    gStyle->SetOptStat(1);

    TCanvas *c3 = new TCanvas("c3", "c3",0,0,400,400);
    c3->SetFillColor(10);
    c3->SetBorderMode(0);
    c3->Divide(2,2);
    c3->Draw();

       ///new: define array 
       const Int_t kMaxTrack = 100;
       Int_t arraysign[kMaxTrack];
       Float_t arraypx[kMaxTrack];
       Float_t arraypy[kMaxTrack];
       Float_t arraypz[kMaxTrack];




// read file $ROOTSYS/tutorials/tree/basic.dat
// this file has 3 columns of float data
   TString dir = gSystem->UnixPathName(__FILE__);
   dir.ReplaceAll("basic_new3.C","");
   dir.ReplaceAll("/./","/");
   ifstream in;
   in.open(Form("%stracks_nofirstline.txt",dir.Data()));

   Int_t ch,n;
   Float_t x,y,z;
   Int_t nlines = 0;
   TFile *f = new TFile("basic_new.root","RECREATE");
   TH1F *h1 = new TH1F("h1","x distribution",100,-4,4);
   TH1F *h2 = new TH1F("h2","pt distribution",100,0,4);

   TNtuple *ntuple = new TNtuple("ntuple","data from ascii file","n:ch:x:y:z");

   while (1) {
      in >> n >> ch >> x >> y >> z;
      if (!in.good()) break;
      if (nlines < 5) printf("n = %2i, ch = %2i, x=%8f, y=%8f, z=%8f\n",n,ch,x,y,z);
      h1->Fill(x);
      ntuple->Fill(n,ch,x,y,z);

      ///new: fill array
      arraysign[nlines] = ch;
      arraypx[nlines]   = x;
      arraypy[nlines]   = y;
      arraypz[nlines]   = z;


      nlines++;

      h2->Fill(sqrt((x*x) + (y*y)));

      //cout << " px+py =" << x+y << endl;
   }
   printf(" found %d points\n",nlines);

   ///new: print statement
   cout<<" new :px at position 3 " <<arraypx[2]<<endl;
 //  cout<<" ntuple " <<ntuple->GetV1(1)<<endl;


   in.close();

   //h1->Draw();
   c3->cd(1);
   h2->SetLineColor(2);
   h2->Draw();

   //h2->Fit("gaus");
   //TF1 *f3 = h2->GetFunction("gaus");


   ////  new : linear fit
   TF1 *f2 = new TF1("f2", "[0] + [1]*x", 0, 2);
   h2->Fit("f2","R");
   cout << " fit function values " << f2->GetParameter(0)<< " and "  << f2->GetParameter(1)<<endl;
   cout << " value of fit function at pt = 1 "  << f2->Eval(1.0)<< endl;
   cout << "  fit integral "  << f2->Integral(0,2)<< endl;


  /// 

  //TF1 *f3 = new TF1("f3", " exp(- x/0.3)");
  //f3->Draw();
 

   c3->cd(2);
   h1->Draw();
   



   f->Write();
}