void drawMultipleTF2(void)
{

TH2F *h2 = new TH2F("h2", "h2", 10, 0, 10, 10, 0, 10);

double topmax = 11;
h2->SetBinContent(3, 3, 2);
h2->SetBinContent(6, 6, 10);
h2->SetStats(false);
h2->SetMaximum(topmax);
h2->Draw("lego2");

TF2 *f2 = new TF2("f2", "[0]/( (x-[1])**2 + (y-[2])**2 + [3]**2 )", 0, 10, 0, 10);

Double_t par[4] = {2, 3, 3, 1};

f2->SetMaximum(topmax);
f2->SetParameters(par);
f2->SetLineColor(3);
f2->DrawCopy("surf same");

par[0] = 10;
par[1] = par[2] = 6;
f2->SetParameters(par);
f2->SetLineColor(4);
f2->DrawCopy("surf same");

}