{
   auto c2 = new TCanvas("c2","c2",0,0,600,400);
   auto f2 = new TF2("f2","0.1+(1-(x-2)*(x-2))*(1-(y-2)*(y-2))",1,3,1,3);
   const Int_t Number = 3;
   Double_t Red[Number]    = { 1.00, 0.00, 0.00};
   Double_t Green[Number]  = { 0.00, 1.00, 0.00};
   Double_t Blue[Number]   = { 1.00, 0.00, 1.00};
   Double_t Length[Number] = { 0.00, 0.50, 1.00 };
   Int_t nb=50;
   TColor::CreateGradientColorTable(Number,Length,Red,Green,Blue,nb);
   f2->SetContour(nb);
   f2->SetLineWidth(1);
   f2->SetLineColor(kBlack);
   f2->Draw("surf1z");
   return c2;
}