void test_plotting() {
  TFile * fin = new TFile("test.root");
  TH3D * h3d = (TH3D*)h3d;
  gStyle->SetCanvasPreferGL(1);
  h3d->Draw("glcolz");
  double * x = new double[3];
  double * y = new double[3];
  double * z = new double[3];

  x[0] = 4600;
  x[1] = 4700;
  x[2] = 4800;

  y[0] = 3200;
  y[1] = 3300;
  y[2] = 3600;

  z[0] = 3600;
  z[1] = 3800;
  z[2] = 3900;

  TGraph2D * g= new TGraph2D(3, x, y, z);
  g->SetMarkerStyle(20);
  g->Draw("same");
  
  
}