TCanvas *Canvas = new TCanvas("DistCanvas", "Legendre polynomials example", 10, 10, 750, 600);
Canvas->SetGrid();
TLegend *leg = new TLegend(0.5, 0.7, 0.4, 0.89);

TF1* L[5];
for(int nu = 0; nu <= 4; nu++)
{
      L[nu]= new TF1("L_0", "ROOT::Math::legendre([0],x)", -1, 1);
      L[nu]->SetParameters(nu, 0.0);
      L[nu]->SetLineStyle(1);
      L[nu]->SetLineWidth(2);
      L[nu]->SetLineColor(nu+1);
}
L[0]->SetMaximum(1);
L[0]->SetMinimum(-1);
L[0]->SetTitle("Legendre polynomials");
leg->AddEntry(L[0]->DrawCopy(), " L_{0}(x)", "l");
leg->AddEntry(L[1]->DrawCopy("same"), " L_{1}(x)", "l");
leg->AddEntry(L[2]->DrawCopy("same"), " L_{2}(x)", "l");
leg->AddEntry(L[3]->DrawCopy("same"), " L_{3}(x)", "l");
leg->AddEntry(L[4]->DrawCopy("same"), " L_{4}(x)", "l");
leg->Draw();

Canvas->cd();

gROOT->GetListOfCanvases()->Draw()