Double_t Bidim(Double_t *x, Double_t *par){  
   
  // Gaussian bidim with 45deg inclination
  Double_t sqrt2=0.707106;
  Double_t arg1=0;  
  Double_t arg2=0;  
  Double_t fitval=0;  
   
  arg1 = x[0]*sqrt2 + x[1]*sqrt2;
  arg2 = (-x[0]*sqrt2 + x[1]*sqrt2)/2;
  fitval = TMath::Exp(-0.5*arg1*arg1)*TMath::Exp(-0.5*arg2*arg2);  
  return fitval;  
 
}

Double_t fitf(Double_t *x, Double_t *par)
{
   Double_t arg = 0;
   Double_t fitval = par[1]*x[0]+par[0];
   return fitval;
}

void Doplot() {


  TH2F *plot1 = new TH2F("plot1","",100,-6,6,100,-6,6);//grid1 for the plots
  TH2F *plot2 = new TH2F("plot2","",300,-6,6,100,-2,2);//grid2 for the plots
  TF2 *mybidim = new TF2("bidim",Bidim,-3,3,-3,3,1);//bidim to plot
  TF1 *myline = new TF1("myline",fitf,-3,3,2);//line going through major axis
  myline->SetParameters(0,-1);
  mybidim->SetContour(4);
  
  
  c1 = new TCanvas("c1","",300,10,600,700);
  c1.Draw();
  
  plot1.Draw();
  mybidim->Draw("same");
  myline->Draw("same");
  
  c2 = new TCanvas("c2","",300,10,600,700);
  c2.Draw();
  
  plot2.Draw();
  mybidim->Draw("same");
  myline->Draw("same");
  

}