// tutorial illustrating the use of TMath::GammaDist and TMath::LogNormal
//Author: Anna Kreshuk
void mathGammaNormal(){
TCanvas *myc = new TCanvas("c1","gamma and lognormal",10,10,600,800);
myc->Divide(1,2);
TPad *pad1 = (TPad *)myc->cd(1);
pad1->SetLogy();
pad1->SetGrid();
//TMath::GammaDist
TF1 *fgamma = new TF1("fgamma", "TMath::GammaDist(x, [0], [1], [2])", 0, 10);
fgamma->SetParameters(0.5, 0, 1);
TF1 *f1 = fgamma->DrawCopy();
f1->SetMinimum(1e-5);
f1->SetLineColor(kRed);
fgamma->SetParameters(1, 0, 1);
TF1 *f2 = fgamma->DrawCopy("same");
f2->SetLineColor(kGreen);
fgamma->SetParameters(2, 0, 1);
TF1 *f3 = fgamma->DrawCopy("same");
f3->SetLineColor(kBlue);
fgamma->SetParameters(5, 0, 1);
TF1 *f4 = fgamma->DrawCopy("same");
f4->SetLineColor(kMagenta);
TLegend *legend1 = new TLegend(.2,.15,.5,.4);
legend1->AddEntry(f1,"gamma = 0.5 mu = 0 beta = 1","l");
legend1->AddEntry(f2,"gamma = 1 mu = 0 beta = 1","l");
legend1->AddEntry(f3,"gamma = 2 mu = 0 beta = 1","l");
legend1->AddEntry(f4,"gamma = 5 mu = 0 beta = 1","l");
legend1->Draw();
//TMath::LogNormal
TPad *pad2 = (TPad *)myc->cd(2);
pad2->SetLogy();
pad2->SetGrid();
TF1 *flog = new TF1("flog", "TMath::LogNormal(x, [0], [1], [2])", 0, 5);
flog->SetParameters(0.5, 0, 1);
TF1 *g1 = flog->DrawCopy();
g1->SetLineColor(kRed);
flog->SetParameters(1, 0, 1);
TF1 *g2 = flog->DrawCopy("same");
g2->SetLineColor(kGreen);
flog->SetParameters(2, 0, 1);
TF1 *g3 = flog->DrawCopy("same");
g3->SetLineColor(kBlue);
flog->SetParameters(5, 0, 1);
TF1 *g4 = flog->DrawCopy("same");
g4->SetLineColor(kMagenta);
TLegend *legend2 = new TLegend(.2,.15,.5,.4);
legend2->AddEntry(g1,"sigma = 0.5 theta = 0 m = 1","l");
legend2->AddEntry(g2,"sigma = 1 theta = 0 m = 1","l");
legend2->AddEntry(g3,"sigma = 2 theta = 0 m = 1","l");
legend2->AddEntry(g4,"sigma = 5 theta = 0 m = 1","l");
legend2->Draw();
}