Dear Rooters,
I’d like to draw the residuals of a fit just below the graph of the fit itself.
Moreover the two graphs should share the same X axis.
An example is attached.
Do you know how to set the second pad so that something similar can be created ?
Thanks in advance,
Marco
see example below.
see also $ROOTSYS/tutorials/fit/ConfidenceIntervals.C
Rene
[code]void residuals() {
gStyle->SetOptStat(0);
TCanvas *c1 = new TCanvas(“c1”,“c1”,800,800);
TPad *pad1 = new TPad(“pad1”,“pad1”,0,0.33,1,1);
TPad *pad2 = new TPad(“pad2”,“pad2”,0,0,1,0.33);
pad1->SetBottomMargin(0.00001);
pad1->SetBorderMode(0);
pad1->SetLogy();
pad2->SetTopMargin(0.00001);
pad2->SetBottomMargin(0.1);
pad2->SetBorderMode(0);
pad1->Draw();
pad2->Draw();
pad1->cd();
Double_t xmin = 0.3;
Double_t xmax = 6;
TF1 *f1 = new TF1(“f1”,"[0]*TMath::Gaus(x,[1],[2])",xmin,xmax);
f1->SetParameters(1,1.7,1.5);
TH1F *h1 = new TH1F(“h1”,“NGC1275”,100,xmin,xmax);
h1->GetYaxis()->SetLabelFont(63);
h1->GetYaxis()->SetLabelSize(16);
h1->FillRandom(“f1”,1000);
h1->Fit(“f1”);
pad2->cd();
TH1F *h2 = new TH1F(“h2”,“residuals”,100,xmin,xmax);
h2->GetXaxis()->SetLabelFont(63);
h2->GetXaxis()->SetLabelSize(16);
h2->GetXaxis()->SetTitle(“channel energy (keV)”);
h2->GetYaxis()->SetLabelFont(63);
h2->GetYaxis()->SetLabelSize(16);
for (Int_t i=1;i<=100;i++) {
Double_t diff = h1->GetBinContent(i)-f1->Eval(h1->GetBinCenter(i));
h2->SetBinContent(i,diff);
}
h2->Draw();
c1->cd();
}[/code]