//______________________________________________________________________________
void Fit(TH1* h, Double_t* outPos, Double_t* outFWHM)
{
// Perform fit.
Char_t tmp[256];
Double_t x1 = 50;
Double_t x2 = 230;
TF1* func = new TF1("func", "gaus(0)+pol5(3)", x1, x2);
func->SetParameters(h->GetMaximum(), 135, 8, 1, 1, 0.1, 0.1);
func->SetLineColor(kBlue);
func->SetParLimits(1, 130, 140);
func->SetParLimits(2, 1, 15);
h->Fit(func, "RBQO");
// get position and FWHM
fPi0Pos = func->GetParameter(1);
*outPos = fPi0Pos;
*outFWHM = 2.35*func->GetParameter(2);
// indicator line
TLine* line = new TLine();
line->SetLineWidth(2);
line->SetX1(fPi0Pos);
line->SetX2(fPi0Pos);
line->SetY1(0);
line->SetY2(h->GetMaximum());
TF1* fBG = new TF1("funcBG", "pol5", x1, x2);
for (Int_t i = 0; i < 6; i++) fBG->SetParameter(i, func->GetParameter(3+i));
fBG->SetLineColor(kRed);
// draw
h->GetXaxis()->SetRangeUser(0, 300);
h->Draw();
func->Draw("same");
fBG->Draw("same");
line->Draw("same");
}
//______________________________________________________________________________
void Fit(TH1* h, Double_t* outPos, Double_t* outFWHM)
{
// Perform fit.
Char_t tmp[256];
// delete old function
TF1* func = new TF1(tmp, "pol1+gaus(2)");
func->SetLineColor(2);
// estimate peak position
Double_t fPi0Pos = h->GetBinCenter(h->GetMaximumBin());
// configure fitting function
func->SetRange(fPi0Pos - 0.8, fPi0Pos + 0.8);
func->SetLineColor(2);
func->SetParameters( 0.1, 0.1, h->GetMaximum(), 0, 0.1);
Int_t fitres = h->Fit(func, "RB0Q");
// get position and FWHM
fPi0Pos = func->GetParameter(3);
*outPos = fPi0Pos;
*outFWHM = 2.35*func->GetParameter(4);
// indicator line
TLine* line = new TLine();
line->SetX1(fPi0Pos);
line->SetX2(fPi0Pos);
line->SetY1(0);
line->SetY2(h->GetMaximum());
// draw
h->GetXaxis()->SetRangeUser(-3, 3);
h->Draw();
func->Draw("same");
line->Draw("same");
}
