Problem in linking ExRootAnalysis libraries

ROOT
1

Hello,
I’m trying to analyse a STDHEP file converted with ExRootAnalysis. I’ve put in my code the following lines:

gSystem->Load("/userhome/msco/aMC/MG5_aMC_v2_2_3/ExRootAnalysis/libExRootAnalysis.so");
gSystem->Load(“libPhysics”);

if I run my macro with .x analysys.cxx, it works fine. When I try to compile it, ROOT fails to load the shared library.
I’ve searched over the internet and, as far as I’ve understood, I should modify my .rootrc configuration file, but I was not able to do it. Could someone help me finding an easy way to let ROOT load the librarary properly?
Thank you in advance.
Cheers,
Matteo

2

Hi Matteo,

could you provide the macro, the error and the root version you are using?

Cheers,
Danilo

3

Sure, the version of ROOT I’m using is:

ROOT 5.34/30 (v5-34-30@v5-34-30, Apr 23 2015, 18:31:46 on linuxx8664gcc)

CINT/ROOT C/C++ Interpreter version 5.18.00, July 2, 2010

and here is a minimal version of my macro which reproduces the error:

#include <TSystem.h>
#include <TLorentzVector.h>
#include <TMath.h>
#include <TChain.h>
#include <TFile.h>
#include <TClonesArray.h>
#include <iostream>
using namespace std;
void analisi(){
//   Load shared library
  gSystem->Load("/home/matteo/MG5_aMC_v2_2_3/ExRootAnalysis/libExRootAnalysis.so");
  gSystem->Load("libPhysics");

  // Create chain of root trees
  TChain c_lhe("LHEF");
  c_lhe.Add("lhe.root");

  TChain c_hep("STDHEP");
  c_hep.Add("hep.root");


  Int_t           Particle_size;
  // Create object of class ExRootTreeReader
  ExRootTreeReader *lheReader = new ExRootTreeReader(&c_lhe);
  ExRootTreeReader *hepReader = new ExRootTreeReader(&c_hep);
  Long64_t numberOfEntries = lheReader->GetEntries();

  cout<<numberOfEntries<<"  eventi"<<endl;

  // Get pointers to branches used in this analysis
  TClonesArray *branchParticle = lheReader->UseBranch("Particle");
  TClonesArray *branchRwgt = lheReader->UseBranch("Rwgt");
  TClonesArray *branchGenParticle = hepReader->UseBranch("GenParticle");
  //array contenenti i pesi
  Double_t w_cent, *w_scale, *w_pdf;
  Int_t scale, pdf;
  Int_t num_pdf;


  scale=1;
  pdf=1;

//determina il numero di variazioni
  if (scale==1)
     w_scale=new Double_t[8];
  if (pdf==1){
     if (scale==1){
        lheReader->ReadEntry(0);
        num_pdf=branchRwgt->GetEntries()-9;
        w_pdf=new Double_t[num_pdf];
     }
     else{
        lheReader->ReadEntry(0);
        num_pdf=branchRwgt->GetEntries()-1;
        w_pdf=new Double_t[num_pdf];
     }
  }
   
 }

and here is the error output:

root [0] .x analisi.cxx+
Info in <TUnixSystem::ACLiC>: creating shared library /home/matteo/analysis_MG5/fraffaa/./analisi_cxx.so
In file included from /home/matteo/analysis_MG5/fraffaa/analisi_cxx_ACLiC_dict.h:34:0,
                 from /home/matteo/analysis_MG5/fraffaa/analisi_cxx_ACLiC_dict.cxx:17:
/home/matteo/analysis_MG5/fraffaa/./analisi.cxx: In function ‘void analisi()’:
/home/matteo/analysis_MG5/fraffaa/./analisi.cxx:26:3: error: ‘ExRootTreeReader’ was not declared in this scope
   ExRootTreeReader *lheReader = new ExRootTreeReader(&c_lhe);
   ^
/home/matteo/analysis_MG5/fraffaa/./analisi.cxx:26:21: error: ‘lheReader’ was not declared in this scope
   ExRootTreeReader *lheReader = new ExRootTreeReader(&c_lhe);
                     ^
/home/matteo/analysis_MG5/fraffaa/./analisi.cxx:26:37: error: expected type-specifier before ‘ExRootTreeReader’
   ExRootTreeReader *lheReader = new ExRootTreeReader(&c_lhe);
                                     ^
/home/matteo/analysis_MG5/fraffaa/./analisi.cxx:27:21: error: ‘hepReader’ was not declared in this scope
   ExRootTreeReader *hepReader = new ExRootTreeReader(&c_hep);
                     ^
/home/matteo/analysis_MG5/fraffaa/./analisi.cxx:27:37: error: expected type-specifier before ‘ExRootTreeReader’
   ExRootTreeReader *hepReader = new ExRootTreeReader(&c_hep);
                                     ^
g++: error: /home/matteo/analysis_MG5/fraffaa/analisi_cxx_ACLiC_dict.o: File o directory non esistente
Error in <ACLiC>: Compilation failed!
Error: Function analisi() is not defined in current scope  :0:
*** Interpreter error recovered ***
4

In the “current” subdirectory (in which you work), create a “rootlogon.C” file: { std::cout << "... rootlogon.C ... loading libraries ..." << std::endl; gSystem->Load("/home/matteo/MG5_aMC_v2_2_3/ExRootAnalysis/libExRootAnalysis.so"); gSystem->Load("libPhysics"); } and in your “analisi.cxx” file add an appropriate #include for the “ExRootTreeReader” class -> maybe something like:
#include “ExRootTreeReader.h”

5

Thank you very much, the error is gone.
I had to include the header with its absolute path

6

Instead of “#include absolute path” in your source code, add in the “rootlogon.C” something like:
gInterpreter->AddIncludePath("/full/path/to/all/your/ExRootAnalysis/includes/directory");
and then in your “analisi.cxx”, you can simply:
#include “SomeIncludeFile.h”

7

Perfect, this is even simpler and faster.
Thank you again

8

Just for completeness … instead of:
gInterpreter->AddIncludePath("/some/directory");
you can also (note “-I” below):
gSystem->AddIncludePath("-I/some/directory");