void CDF_77_33()
{
TCanvas *c1 = new TCanvas();

 ifstream file ("Mean v 77.3395.dat", ios::in);
 int loop=0;
  string x, y;
  double xx[22], yy[22], yy2[22], yy3[22] = {0.};
  
  while(!file.eof())
  {
  file >> x >> y;
  cout<<x<<" "<<y<<endl;
  
  if(loop>0) {
   
   xx[loop-1]=std::stod(x);
   yy[loop-1]=std::stod(y);
   
   }
   loop++;
   }
  
  double sum=0;
  for(int m=0;m<loop-1;m++){
  sum+=yy[m];
  }  
 
  for(int m=0;m<loop-1;m++)
  {
    yy2[m] = yy[m] / sum;
    for (int n=0;n<=m;n++) yy3[m] += yy2[n];
    }
  TGraph *grCDF = new TGraph(22, xx, yy3);
  grCDF->SetTitle(";Neutron Velocity (m/s);Cumulative Distributions");
  grCDF->GetYaxis()->SetRangeUser(0.,1.1);
  grCDF->GetXaxis()->CenterTitle(true);
  grCDF->GetYaxis()->CenterTitle(true);
  grCDF->Draw("*AP");

  // create a histograms with input data from dat file
  TH1F *h = new TH1F("",";Neutron Velocity (m/s);Entries",22,64,91);
  for (int i=0;i<22;i++) {
    h->SetBinContent(h->FindBin(xx[i]), yy[i]);
  }
  //h->SetBinContent(h->FindBin(xx[i]), yy[i]);
  // Now, try to fill a new histograms with random velocity:
  TH1F *h_new = new TH1F("",";Neutron Velocity (m/s);Entries",500,64,91);
  for (int i=0;i<100000;i++) {
  float randomVelocity = h->GetRandom();
  for (int bin=1;bin<=h_new->GetNbinsX();bin++) {
  if (randomVelocity<=h_new->GetXaxis()->GetBinCenter(bin)-h_new->GetXaxis()->GetBinWidth(bin)) {
      h_new->AddBinContent(bin);
      }
    }
  }
  h_new->Scale(1/100000.);
  
  h_new->SetFillColor(kOrange-4);
  h_new->Draw("same");
}