/// Compilation:
/// g++ -I/usr/local/share/root/root_v5_30_03/include -I ../Include -c -o test_root.o test_root_pb.cpp
/// g++ test_root.o -L/usr/local/share/root/root_v5_30_03/lib -lGpad -lHist -lGraf -lGraf3d -lTree -lRint -lPostscript -lMatrix -lPhysics -lMathCore -lRIO -lNet -lThread -lCore -lCint -lpthread -Wl,-rpath,/usr/local/share/root/root_v5_30_03/lib -lm -ldl  -o test_root


// The following include files contain the usual ones.
#include "../Include/all_includes.h"
#include "../Include/root_libs.h"


// Global variable meant to be used in other functions.
static TGraph grtest;

int main(int argc, const char* argv[])
{
  using namespace std;

  TPostScript *myps = new TPostScript("test_root.ps",111);
  TCanvas c1("c1","c1",500,500);

  TH2D *hh = new TH2D("hres","hres",2,0,100,2,0,110);
  hh->SetXTitle("x");
  hh->SetYTitle("y");

  double x,y;

  int i,j,Ni=10,Nj=100;

  TGraph grlocal;
  grlocal = TGraph::TGraph(Nj+1);
  grtest = TGraph::TGraph(Nj+1);

  for(i=0;i<=Ni;++i){

    for(j=0;j<=Nj;++j){
      x = j;
      y = 2*i+j;
      grlocal.SetPoint(j,x,y);
      grtest.SetPoint(j,x,2*y);
    }

    hh->Draw();

    // When the line below is commented, there is no warning message anymore.
    grlocal.Draw("l");

    // For some reason, I have to initialize grtest at each step in a loop
    for(j=0;j<3;++j){
      grtest = grlocal;
      //
      // ... here, call any function using grtest and potentially modifying it
      //
      grtest.SetLineColor(kRed);
      grtest.SetLineStyle(2);
      grtest.Draw("l");
      c1.Update();
      }
  }

  myps->Close(); delete myps; delete hh;

  return 0;
}