Ratioplot 2

Example of a fit residual plot.

Creates a histogram filled with random numbers from a gaussian distribution and fits it with a standard gaussian function. The result is passed to the TRatioPlot constructor. Additionally, after calling TRatioPlot::Draw the upper and lower y axis titles are modified. Confidence interval bands are automatically drawn on the bottom (but can be disabled by draw option nobands.

Author: Paul Gessinger
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Thursday, May 19, 2022 at 08:14 AM.

In [1]:
gStyle->SetOptStat(0);
auto c1 = new TCanvas("c1", "fit residual simple");
auto h1 = new TH1D("h1", "h1", 50, -5, 5);
h1->FillRandom("gaus", 2000);
h1->Fit("gaus", "0");
h1->GetXaxis()->SetTitle("x");
auto rp1 = new TRatioPlot(h1);
rp1->Draw();
rp1->GetLowerRefYaxis()->SetTitle("ratio");
rp1->GetUpperRefYaxis()->SetTitle("entries");

 FCN=22.1778 FROM MIGRAD    STATUS=CONVERGED      54 CALLS          55 TOTAL
                     EDM=1.30715e-07    STRATEGY= 1      ERROR MATRIX ACCURATE 
  EXT PARAMETER                                   STEP         FIRST   
  NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE 
   1  Constant     1.58988e+02   4.47298e+00   8.40573e-03   1.35230e-04
   2  Mean         6.62197e-03   2.25355e-02   5.27819e-05  -8.76854e-04
   3  Sigma        9.93481e-01   1.69678e-02   1.05689e-05   9.41157e-02

Draw all canvases

In [2]:
gROOT->GetListOfCanvases()->Draw()