void plot_yields(){
  ifstream in("omega_yields.dat");
  double Ebeam[24];
  double threepi[24],dthreepi[24],threeg[24],dthreeg[24];
  for (int i=0;i<24;i++) Ebeam[i]=7.1+0.2*i;
  for (int i=0;i<24;i++){
    in >> threeg[i];
    in >> dthreeg[i];
    in >> threepi[i];
    in >> dthreepi[i];
  }
  in.close();
  
  TCanvas *c1=new TCanvas();
  TH2F *h=new TH2F("h","h",2,7,11.8,10,0,200);
  h->Draw();
  TGraphErrors *g1=new TGraphErrors(24,Ebeam,0,threeg,dthreeg);
  g1->Draw();



}