CrystalBall

Example of CrystalBall Function and its distribution (pdf and cdf)

Author: Lorenzo Moneta
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, August 17, 2022 at 09:34 AM.

In [1]:
auto c1 = new TCanvas();
c1->Divide(1,3);

crystal ball function

In [2]:
c1->cd(1);

auto f1  = new TF1("f1","crystalball",-5,5);
f1->SetParameters(1, 0, 1, 2, 0.5);
f1->SetLineColor(kRed);
f1->Draw();

use directly the functionin ROOT::MATH note that the parameters definition is different is (alpha, n sigma, mu)

In [3]:
auto f2 = new TF1("f2","ROOT::Math::crystalball_function(x, 2, 1, 1, 0)",-5,5);
f2->SetLineColor(kGreen);
f2->Draw("same");
auto f3 = new TF1("f3","ROOT::Math::crystalball_function(x, 2, 2, 1, 0)",-5,5);
f3->SetLineColor(kBlue);
f3->Draw("same");

auto legend = new TLegend(0.7,0.6,0.9,1.);
legend->AddEntry(f1,"N=0.5 alpha=2","L");
legend->AddEntry(f2,"N=1   alpha=2","L");
legend->AddEntry(f3,"N=2   alpha=2","L");
legend->Draw();

c1->cd(2);
auto pdf1  = new TF1("pdf","crystalballn",-5,5);
pdf1->SetParameters(2, 0, 1, 2, 3);
pdf1->Draw();
auto pdf2 = new TF1("pdf","ROOT::Math::crystalball_pdf(x, 3, 1.01, 1, 0)",-5,5);
pdf2->SetLineColor(kBlue);
pdf2->Draw("same");
auto pdf3 = new TF1("pdf","ROOT::Math::crystalball_pdf(x, 2, 2, 1, 0)",-5,5);
pdf3->SetLineColor(kGreen);
pdf3->Draw("same");

legend = new TLegend(0.7,0.6,0.9,1.);
legend->AddEntry(pdf1,"N=3    alpha=2","L");
legend->AddEntry(pdf2,"N=1.01 alpha=3","L");
legend->AddEntry(pdf3,"N=2    alpha=3","L");
legend->Draw();

c1->cd(3);
auto cdf  = new TF1("cdf","ROOT::Math::crystalball_cdf(x, 1.2, 2, 1, 0)",-5,5);
auto cdfc  = new TF1("cdfc","ROOT::Math::crystalball_cdf_c(x, 1.2, 2, 1, 0)",-5,5);
cdf->SetLineColor(kRed-3);
cdf->SetMinimum(0.);
cdf->SetMaximum(1.);
cdf->Draw();
cdfc->SetLineColor(kMagenta);
cdfc->Draw("Same");

legend = new TLegend(0.7,0.7,0.9,1.);
legend->AddEntry(cdf,"N=1.2 alpha=2","L");
legend->AddEntry(cdfc,"N=1.2 alpha=2","L");
legend->Draw();

Draw all canvases

In [4]:
gROOT->GetListOfCanvases()->Draw()