void MakeRandom()
{
  // start randomnumber generator:
 srand( time(NULL) );

 // create histogramm:
 double UpperLimit=1.0;
 double LowerLimit=0.0;
 double NumberOfBins=1000;
 TH1D *RandomHist=new TH1D("RandomHist","RandomHist",NumberOfBins,LowerLimit,UpperLimit);
 
 //set total number of random-numbers to be generated
 int rand_max=10000000;
 
 // create random numbers:
 for (int i=0;i<rand_max;i++){
   double r=rand();
   // we want to have randomnumbers from 0.0-1.0:
   r=r/2.1475e+09;
   RandomHist->Fill(r);
 }

 // normalize histogramm:
 //double A=RandomHist->Integral();
 //RandomHist->Scale(1/A);

 // produce jpg:
 TCanvas *can=new TCanvas("RandomCan","RandomCan",800,600);
 RandomHist->Draw();
 can->Print("RandomHist.jpg");
}