#include <TFile.h>
#include <TNtuple.h>
#include <TH2.h>
#include <TRandom.h>

int main()
{
   TFile *hfile = new TFile("hsimple.root","RECREATE");

   // Create some histograms, a profile histogram and an ntuple
   TH1F *hpx       = new TH1F("hpx","This is the px distribution",100,-4,4);
   TH2F *hpxpy     = new TH2F("hpxpy","py vs px",40,-4,4,40,-4,4);
   TNtuple *ntuple = new TNtuple("ntuple","Demo ntuple","px:py:pz:random:i");

   TRandom r;
   Float_t px, py, pz;
   for (Int_t i = 0; i < 25000; i++) {
      r.Rannor(px,py);
      pz = px*px + py*py;
      Float_t random = r.Rndm(1);
      hpx->Fill(px);
      hpxpy->Fill(px,py);
      ntuple->Fill(px,py,pz,random,i);
   }
   hfile->Write();
}