Logo ROOT   6.12/07
Reference Guide
qa2.C File Reference

Detailed Description

View in nbviewer Open in SWAN Test generation of random numbers distributed according to a function defined by the user

pict1_qa2.C.png
Processing /mnt/build/workspace/root-makedoc-v612/rootspi/rdoc/src/v6-12-00-patches/tutorials/fit/qa2.C...
void qa2() {
//Fill a 1-D histogram from a parametric function
TCanvas *c1 = new TCanvas("c1","The FillRandom example",0,0,700,500);
gBenchmark->Start("fillrandom");
//
// A function (any dimension) or a formula may reference
// an already defined formula
//
TFormula *form1 = new TFormula("form1","abs(sin(x)/x)");
TF1 *sqroot = new TF1("sqroot","x*gaus(0) + [3]*form1",0,10);
sqroot->SetParameters(10,4,1,20);
//
// Create a one dimensional histogram (one float per bin)
// and fill it following the distribution in function sqroot.
//
TH1F *h1f = new TH1F("h1f","Test random numbers",200,0,10);
h1f->SetFillColor(45);
h1f->FillRandom("sqroot",100000);
h1f->Draw();
TPaveLabel *lfunction = new TPaveLabel(5,39,9.8,46,"The sqroot function");
lfunction->SetFillColor(41);
c1->SetGridx();
c1->SetGridy();
h1f->SetDirectory(0);
c1->Update();
sqroot->SetParameters(200,4,1,20);
}
Author
Rene Brun

Definition in file qa2.C.