   TCanvas * c1 = new TCanvas("c1","Canvas");
   c1->SetGridx();
   c1->SetGridy();
   TF1 *sqroot = new TF1("sqroot", "x*gaus(0) + [3]*form1", 0.0, 10.0);
   sqroot->SetLineColor(4);
   sqroot->SetLineWidth(6);
   sqroot->SetParameters(10.0, 4.0, 1.0, 20.0);
   sqroot->Print();

   TH1D *h1d = new TH1D("h1d", "Test random numbers", 200, 0.0, 10.0);
   h1d->FillRandom("sqroot", 10000);
   h1d->Fit("sqroot");
