{ gROOT->Reset(); // Draw histos filled by Geant4 simulation // TFile f = TFile("testem5.root"); TCanvas* c1 = new TCanvas("c1", " "); TH1D* hist1 = (TH1D*)f.Get("13"); hist1->Draw("HIST"); c1->SetLogy(1); c1->cd(); c1->Update(); hist1->Draw("HIST"); }