doc/v606/fillrandom_8C.html

void fillrandom() {

   TCanvas *c1 = new TCanvas("c1","The FillRandom example",200,10,700,900);

   c1->SetFillColor(18);


   auto pad1 = new TPad("pad1","The pad with the function",0.05,0.50,0.95,0.95,21);

   auto pad2 = new TPad("pad2","The pad with the histogram",0.05,0.05,0.95,0.45,21);

   pad1->Draw();

   pad2->Draw();

   pad1->cd();


   gBenchmark->Start("fillrandom");

   //

   // A function (any dimension) or a formula may reference

   // an already defined formula

   //

   auto form1 = new TFormula("form1","abs(sin(x)/x)");

   auto sqroot = new TF1("sqroot","x*gaus(0) + [3]*form1",0,10);

   sqroot->SetParameters(10,4,1,20);

   pad1->SetGridx();

   pad1->SetGridy();

   pad1->GetFrame()->SetFillColor(42);

   pad1->GetFrame()->SetBorderMode(-1);

   pad1->GetFrame()->SetBorderSize(5);

   sqroot->SetLineColor(4);

   sqroot->SetLineWidth(6);

   sqroot->Draw();

   auto lfunction = new TPaveLabel(5,39,9.8,46,"The sqroot function");

   lfunction->SetFillColor(41);

   lfunction->Draw();

   c1->Update();


   //

   // Create a one dimensional histogram (one float per bin)

   // and fill it following the distribution in function sqroot.

   //

   pad2->cd();

   pad2->GetFrame()->SetFillColor(42);

   pad2->GetFrame()->SetBorderMode(-1);

   pad2->GetFrame()->SetBorderSize(5);

   auto h1f = new TH1F("h1f","Test random numbers",200,0,10);

   h1f->SetFillColor(45);

   h1f->FillRandom("sqroot",10000);

   h1f->Draw();

   c1->Update();

   //

   // Open a ROOT file and save the formula, function and histogram

   //

   TFile myfile("fillrandom.root","RECREATE");

   form1->Write();

   sqroot->Write();

   h1f->Write();

   gBenchmark->Show("fillrandom");

}