{
  gROOT->SetStyle("Plain");
  TCanvas c("c", "",600, 600);
  c.SetTheta(30);
  c.SetPhi(50);
  gStyle->SetOptStat(0);
  gStyle->SetHistTopMargin(0);
  gStyle->SetOptTitle(kFALSE);
  TF2 f("f", "[0]*cos(x)*cos(y)", -1, 1, -1, 1);
  f.SetParameter(0, 1);
  double s = 1./f.Integral(-1, 1, -1, 1);
  f.SetParameter(0, s);
  f.SetNpx(50);
  f.SetNpy(50);
  double x[11]={-0.5, -0.5, -0.5, -0.5, -0.5, -0.5, -0.5, -0.5, -0.5, -0.5, -0.5};
  double y[11]={-0.985, -0.8, -0.6, -0.4, -0.2,  0.0,  0.2,  0.4,  0.6,  0.8,  0.985};
  double z[11]={0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3};
  for(int i = 0; i < 11; ++i) z[i] = s*cos(x[i])*cos(y[i]);
  TGraph2D g2(11, x, y, z);
  g2.SetTitle("g2");
  g2.SetName("g2");
  double xx[2]={-0.5, -0.5};
  double yy[2]={-0.985, -0.985};
  double zz[2]={0.11, s*cos(-0.5)*cos(-0.985)};
  TGraph2D l2(2, xx, yy, zz);
  l2.SetTitle("l2");
  l2.SetName("l2");
  f.SetTitle("dP/dxdy=f(x,y)");
  f.SetLineWidth(1);
  f.SetLineColor(kAzure-2);

  f.GetXaxis()->SetTitle("x");
  f.GetXaxis()->SetTitleOffset(1.4);
  f.GetXaxis()->SetTitleSize(0.04);
  f.GetXaxis()->CenterTitle();
  f.GetXaxis()->SetNdivisions(505);
  f.GetXaxis()->SetTitleOffset(1.3);
  f.GetYaxis()->SetTitle("y");
  f.GetYaxis()->CenterTitle(); 
  f.GetYaxis()->SetTitleOffset(1.4);
  f.GetYaxis()->SetTitleSize(0.04);
  f.GetYaxis()->SetTitleOffset(1.3);
  f.GetYaxis()->SetNdivisions(505);
  f.GetZaxis()->SetTitle("dP/dx");
  f.GetZaxis()->CenterTitle();
  f.GetZaxis()->SetTitleOffset(1.3);
  f.GetZaxis()->SetNdivisions(505);
  f.GetZaxis()->SetTitleSize(0.04);
  f.GetXaxis()->SetLabelSize(0.03);
  f.GetYaxis()->SetLabelSize(0.03);
  f.GetZaxis()->SetLabelSize(0.03);
  f.Draw("surf");
  g2.SetLineColor(kRed);
  g2.SetLineWidth(3);
  g2.Draw("sameline"); 
  l2.SetLineColor(kRed);
  l2.SetLineStyle(2);
  l2.SetLineWidth(1);
  l2.Draw("sameline");
  TLatex txt(0.05, 0, "f(y|x_{0})");
  txt.SetTextColor(kRed);
  txt.Draw();                                                                            
  TLatex txt1(0.12, 0.52, "f(x,y)");
  txt1.SetTextColor(kBlue);
  txt1.Draw();                                                                            
  TLatex txt2(0.28, -0.76, "x_{0}");
  txt2.SetTextColor(kRed);
  txt2.Draw();                                                                            
  c.SaveAs("../figures/2dpdfcond.pdf");
}