| Geant4 Cross Reference |
1 // 1
2 // Fit of longitudinal profile with Gamma func
3 // See Review of Particles Physics - Electroma
4 //
5 //....oooOO0OOooo........oooOO0OOooo........oo
6
7 Double_t GammaFunction(Double_t* t, Double_t*
8 if (ROOT::TMath::Gamma(params[0]) != 0 ) {
9 return (100 * pow(params[1],params[0]) / R
10 * pow(t[0],(params[0]-1)) * exp (-p
11 } else {
12 return 0;
13 }
14 }
15
16 //....oooOO0OOooo........oooOO0OOooo........oo
17
18 void GammaFit() {
19 cout
20 << "Try fit [100*pow(b,a)/ROOT::TMath::Gamma
21 << endl;
22 TFile* f = new TFile("93ref0.root");
23 TH1D* h1 = (TH1D*) f->Get("4");
24 //put error in h1
25 TH1D* h2 = (TH1D*) f->Get("5");
26 int nmax = h1->GetNbinsX();
27 for (int n=0; n<nmax; n++) {
28 Double_t er = h2->GetBinContent(n);
29 h1->SetBinError(n,er);
30 }
31
32 TF1* func = new TF1("fit", GammaFunction,-0.5,
33 func->SetParameter(0,1.);
34 func->SetParameter(1,1.);
35 func->SetParNames("a", "b");
36
37 h1->Fit("fit","r","");
38 h1->SetMarkerColor(kRed);
39 h1->SetMarkerStyle(3);
40 h1->Draw("epl");
41
42 Double_t a = func->GetParameter(0);
43 Double_t b = func->GetParameter(1);
44 Double_t tmax = (a-1)/b;
45
46 // Chi-square distribution
47 double chisq=func->GetChisquare();
48 double ndf=func->GetNDF();
49 double chisqdf=chisq/ndf;
50
51 gStyle->SetOptFit(1111);
52
53 cout << "-------------------------------------
54 cout << "\n Chisquare: " << chisq << " / " <<
55 cout << "\n-----------------------------------
56 cout << "\n a = " << a;
57 cout << "\n b = " << b;
58 cout << "\n tmax = " << tmax;
59 cout << "\n-----------------------------------
60 }
61
62 //....oooOO0OOooo........oooOO0OOooo........oo
63