#include "TVector3.h"
void tree_with_vector()
{
  
  TVector3 vPosition[5];
  int number[5];
  int trajNo = 0;
  
  //intialize
  for(int j=0; j<5; j++) {
    number[j] = 0;
    vPosition[j].SetXYZ(0.,0.,0.);
  }

  ///
  for(int i=0; i<5; i++) {
    
   trajNo = i;
   number[i] = i;
   vPosition[i] = TVector3(i,i+1, i+2);
   // vPosition[i].SetXYZ(i,i+1, i+2);
   
  }
  
  
  ///create the tree
  TFile f("test.root","recreate");
  TTree* t = new TTree("tree","tree with vector");
  
  //
  t->Branch("traj", &trajNo,"trajNo/I");
  t->Branch("Num", number,"number[trajNo]/I");
  t->Branch("vector",vPosition);
  
  
  //
  t->Fill();
  t->Write();
  
}