Double_t g2(Double_t *x, Double_t *par) 
{
   Double_t r1 = x[0]-par[1];
   Double_t r2 = x[1]-par[3];
   if(par[2] != 0)
     r1 /= par[2];
   if(par[4] != 0)
    r2 /= par[4];
   return par[0]*TMath::Exp(-0.5*(r1*r1+r2*r2));
}

void test()
{
   TF2 *f2e = new TF2("f2e", g2, 2, 25, 100, 220, 5);
   f2e->SetParameter(0,  1);
   f2e->SetParameter(1,   2);
   f2e->SetParameter(2,  1);
   f2e->SetParameter(3,   185);
   f2e->SetParameter(4,  6);
   
   f2e->Draw("SURF1");

  Double_t e1x = f2e->Integral(2, 5.5, 165, 215);
  Double_t e2x = f2e->Integral(5.5,  25, 100, 165);
}