//#include "Riostream.h"
void basic() {
//  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();

// read file $ROOTSYS/tutorials/tree/basic.dat
// this file has 3 columns of float data
   TString dir = gSystem->UnixPathName(__FILE__);
   dir.ReplaceAll("basic.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.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);
      nlines++;

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

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

   in.close();

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

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



   f->Write();
}