{
  gStyle->SetOptTitle(0);
 TCanvas *c1 = new TCanvas("c1");
 c1->Clear();
 c1->Divide(2,2);
 c1->cd(1);
TF2 *f1 = new TF2("f1","sqrt(0.5*0.5*(1+pow(1-x,2)*x)*(1+pow(1-y,2)*y)/(1+pow(1-x,2)*x*0.5)/(1+pow(1-y,2)*y*0.5))",0,1.,0,1.);

 f1->GetXaxis()->SetTitle("R_{a}");
 f1->GetYaxis()->SetTitle("R_{b}");
 f1->GetZaxis()->SetTitle("T_{m}");
 f1->GetXaxis()->SetTitleOffset(2.);
 f1->GetYaxis()->SetTitleOffset(2.);
 f1->GetZaxis()->SetTitleOffset(1.25);
 f1->GetXaxis()->CenterLabels();
 f1->GetYaxis()->CenterLabels();
 f1->GetZaxis()->CenterLabels();


 TPaveLabel *pl = new TPaveLabel(-1.1,0.75,-0.3,1,"T_{s}#equiv0.5");
 pl->SetBorderSize(0);
 pl->Draw();


// two contours less than the number of colors in palette
//f2->SetContour(colNum-2);
 f1->Draw("Surf1z");
 pl->Draw();
 c1->cd(2);
 TF2 *f2 = new TF2("f2","sqrt(0.75*0.75*(1+pow(1-x,2)*x)*(1+pow(1-y,2)*y)/(1+pow(1-x,2)*x*0.75)/(1+pow(1-y,2)*y*0.75))",0,1.,0,1.);
// two contours less than the number of colors in palette
//f2->SetContour(colNum-2); 
 f2->GetXaxis()->SetTitle("R_{a}");
 f2->GetYaxis()->SetTitle("R_{b}");
 f2->GetZaxis()->SetTitle("T_{m}"); 
 f2->GetXaxis()->SetTitleOffset(2.);
 f2->GetYaxis()->SetTitleOffset(2.);
 f2->GetZaxis()->SetTitleOffset(1.25);
 f2->GetXaxis()->CenterLabels();
 f2->GetYaxis()->CenterLabels();
 f2->GetZaxis()->CenterLabels();

 f2->Draw("Surf1Z");
 TPaveLabel *pl2 = new TPaveLabel(-1.1,0.75,-0.3,1,"T_{s}#equiv0.75");
 pl2->SetBorderSize(0);
 pl2->Draw();


 c1->cd(3);
TF2 *f3 = new TF2("f3","sqrt(0.9*0.9*(1+pow(1-x,2)*x)*(1+pow(1-y,2)*y)/(1+pow(1-x,2)*x*0.9)/(1+pow(1-y,2)*y*0.9))",0,1.,0,1.);

 f3->GetXaxis()->SetTitle("R_{a}");
 f3->GetYaxis()->SetTitle("R_{b}");
 f3->GetZaxis()->SetTitle("T_{m}");
 f3->GetXaxis()->SetTitleOffset(2.);
 f3->GetYaxis()->SetTitleOffset(2.);
 f3->GetZaxis()->SetTitleOffset(1.25);
 f3->GetXaxis()->CenterLabels();
 f3->GetYaxis()->CenterLabels();
 f3->GetZaxis()->CenterLabels();

// two contours less than the number of colors in palette
//f2->SetContour(colNum-2);
f3->Draw("Surf1Z");

 TPaveLabel *pl3 = new TPaveLabel(-1.1,0.75,-0.3,1,"T_{s}#equiv0.9");
 pl3->SetBorderSize(0);
 pl3->Draw();

 c1->cd(4);
TF2 *f4 = new TF2("f4","sqrt(0.99*0.99*(1+pow(1-x,2)*x)*(1+pow(1-y,2)*y)/(1+pow(1-x,2)*x*0.99)/(1+pow(1-y,2)*y*0.99))",0,1.,0,1.);
// two contours less than the number of colors in palette
//f2->SetContour(colNum-2);

 f4->GetXaxis()->SetTitle("R_{a}");
 f4->GetYaxis()->SetTitle("R_{b}"); 
 f4->GetZaxis()->SetTitle("T_{m}");
 f4->GetXaxis()->SetTitleOffset(2.);
 f4->GetYaxis()->SetTitleOffset(2.);
 f4->GetZaxis()->SetTitleOffset(1.25);
 f4->GetXaxis()->CenterLabels();
 f4->GetYaxis()->CenterLabels();
 f4->GetZaxis()->CenterLabels();



 f4->Draw("Surf1Z");

 TPaveLabel *pl4 = new TPaveLabel(-1.1,0.75,-0.3,1,"T_{s}#equiv0.99");
 pl4->SetBorderSize(0);
 pl4->Draw();
}