Mathcore Vector Float I O

Macro illustrating automatic dictionary generation and I/O with Lorentz Vectors of floats The dictionary for LorentzVector of float is not in the libMathCore, therefore is generated when parsed the file with CINT.

To run this macro you must do

root[0] .L  mathcoreVectorFloatIO.C+
root[1] runIt();

Author: Lorenzo Moneta
This notebook tutorial was automatically generated with ROOTBOOK-izer (Beta) from the macro found in the ROOT repository on Thursday, January 19, 2017 at 04:33 PM.



In [1]:

    
%%cpp -d
#include "TRandom.h"
#include "TStopwatch.h"
#include "TSystem.h"
#include "TFile.h"
#include "TTree.h"
#include "TH1D.h"
#include "TCanvas.h"

#include <iostream>

#include "TLorentzVector.h"

#include "Math/Vector4D.h"


#ifdef __MAKECINT__
#pragma link C++ class ROOT::Math::PxPyPzE4D<float>+;
#pragma link C++ class ROOT::Math::LorentzVector<ROOT::Math::PxPyPzE4D<float> >+;
#pragma link C++ typedef ROOT::Math::XYZTVectorF;
#endif



In [2]:

    
%%cpp -d
// This is a workaround to make sure the namespace is used inside functions
using namespace ROOT::Math;

A helper function is created:



In [3]:

    
%%cpp -d
void write(int n) {

   TRandom R;
   TStopwatch timer;

   TFile f1("mathcoreVectorIO_F.root","RECREATE");

   // create tree
   TTree t1("t1","Tree with new Float LorentzVector");

   XYZTVectorF *v1 = new XYZTVectorF();
   t1.Branch("LV branch","ROOT::Math::XYZTVectorF",&v1);

   timer.Start();
   for (int i = 0; i < n; ++i) {
      double Px = R.Gaus(0,10);
      double Py = R.Gaus(0,10);
      double Pz = R.Gaus(0,10);
      double E  = R.Gaus(100,10);
      v1->SetCoordinates(Px,Py,Pz,E);
      t1.Fill();
   }

   f1.Write();
   timer.Stop();
   std::cout << " Time for new Float Vector " << timer.RealTime() << "  " << timer.CpuTime() << std::endl;
   t1.Print();
}

A helper function is created:



In [4]:

    
%%cpp -d
void read() {

   TRandom R;
   TStopwatch timer;

   TFile f1("mathcoreVectorIO_F.root");

   // create tree
   TTree *t1 = (TTree*)f1.Get("t1");

   XYZTVectorF *v1 = 0;
   t1->SetBranchAddress("LV branch",&v1);

   timer.Start();
   int n = (int) t1->GetEntries();
   std::cout << " Tree Entries " << n << std::endl;
   double etot=0;
   for (int i = 0; i < n; ++i) {
      t1->GetEntry(i);
      etot += v1->E();
   }

   timer.Stop();
   std::cout << " Time for new Float Vector " << timer.RealTime() << "  " << timer.CpuTime() << std::endl;
   std::cout << " E average" << n<< "  " << etot << "  " << etot/double(n) << endl;
}

A helper function is created:



In [5]:

    
%%cpp -d
void runIt() {

#if defined(__CINT__) && !defined(__MAKECINT__)
   gSystem->Load("libMathCore");
   gSystem->Load("libPhysics");
   using namespace ROOT::Math ;

   cout << "This tutorial can run only using ACliC, you must run it by doing: " << endl;
   cout << "\t  .L tutorials/math/mathcoreVectorFloatIO.C+" << endl;
   cout << "\t  runIt()" << endl;
#endif
   int nEvents = 100000;
   write(nEvents);
   read();
}



In [6]:

    
#if defined(__CINT__) && !defined(__MAKECINT__)
gSystem->Load("libMathCore");
gSystem->Load("libPhysics");
using namespace ROOT::Math ;

cout << "This tutorial can run only using ACliC, you must run it by doing: " << endl;
cout << "\t  .L tutorials/math/mathcoreVectorFloatIO.C+" << endl;
cout << "\t  runIt()" << endl;

#endif