void test(){
  TH1F *h1 = new TH1F("h1","h1",8,132.5,212.5);
  h1->Sumw2();

  TH1F *h2 = new TH1F("h2","h2",8,132.5,212.5);
  h2->Sumw2();

  TRandom3 r3;

  double Integral=0, Error=0;

  double w[15]={0.00123, 0.0533, -1.000023, 1.20555, 0.00098007, 0.97087, 2.11193, 0.3098, 0.55, 1.10 , 0.001, 2.345555, 1.5500009, 0.011928, 2.};
  //double w[15]={ 1.,1.,1.,1.,1.,1.,1.,1.,1.,1.,1.,1.,1.,1.,1. };

  for(int i=0; i<8000; i++  )
  {
    for(int j=0; j<15; j++ )
    {
      h1->Fill(r3.Gaus(172.7,9.8), w[j]);
      h2->Fill(r3.Gaus(80.4,14.5), w[j] );

      Integral+= (w[j]);
      Error+= (w[j]*w[j]);
    }
  }

  double Err1=0, Err2=0;
  cout<<"h1->Integral(0,-1) = "<<h1->IntegralAndError(0,-1,Err1)<<" +/- "<<Err1<<"  just sum of weights = "<<Integral<<" +/- "<<sqrt(Error)<<endl;
  cout<<"h2->Integral(0,-1) = "<<h2->IntegralAndError(0,-1,Err2)<<" +/- "<<Err2<<"  just sum of weights = "<<Integral<<" +/- "<<sqrt(Error)<<endl;
}