{
    TCanvas *c1 = new TCanvas("c1","",600,600);
    
    TF2 *func = new TF2("func","exp(-0.5*(x*x+y*y-2*[0]*x*y)/(1-[0]*[0]))",-3,3,-3,3);
    func->SetParameter(0,0.9);
    
    func->SetTitle("");
    func->SetContour(10);
    func->SetNpx(100);
    func->SetNpy(100);
    func->Draw("cont0z");
}