Hi, Currently to access the axis for a TMultiGraph, you first need to draw it and make sure the drawing actually happened. i.e do mg->Draw("ap"); gPad->Update(); Cheers, Philippe -----Original Message----- From: owner-roottalk@pcroot.cern.ch [mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of zaldy Sent: Saturday, August 16, 2003 4:31 AM To: Stanislav Nesterov Cc: roottalk@pcroot.cern.ch Subject: Re: [ROOT] TMultiGraph ... Hi, Thanks for reminding. It was a clerical error while am typing it in roottalk. I re-submit again. I rechecked again my original code Am using the notation "->" not the "." notation. I used ROOT 3.05/05 gcc 3.3.3 Redhat 9.0 /////////////////////////////////////////////////////////// > >Why is the ff. always givves a "illegal pointer" message? > > > > TMultiGraph * mg = new TMultiGraph(); > > TGraph * G[100]; > > ..... > > for (int i ....) { > > mg->Add(G[i]); > > } > > > > mg->Draw("ap"); > > mg->GetXaxis()->SetTitle("TIiiii"); > > gPad->Modified(); > > > > > > > >I wanted to put an X label as well as Y Label. > > > >I tried, TAxis * axis = (TAxis *)mg->GetXaxis(); > > axis->SetTitle("XTITLE"); > > > >But illegal pointer message again. > > > >How ever, I can make this with TGraph. > >Why? Isnt it true that TMultigraph is just related to TGraph? > >Could this be a bug? //////////////////////////////////////////////////////////////////// > > You must be careful with '.' and '->' operators. After *mg = new .... > you can use only '->' notation to resolve object methods and variables, > 'cause 'mg' is the pointer, not the very object. So change mg. to mg-> > everywhere. > > Best regards, > > Stanislav. > > zaldy wrote: > > >Hello, > > > > > >Why is the ff. always givves a "illegal pointer" message? > > > > TMultiGraph * mg = new TMultiGraph(); > > TGraph * G[100]; > > ..... > > for (int i ....) { > > mg.Add(G[i]); > > } > > > > mg.Draw("ap"); > > mg->GetXaxis()->SetTitle("TIiiii"); > > gPad->Modified(); > > > > > > > >I wanted to put an X label as well as Y Label. > > > >I tried, TAxis * axis = (TAxis *)mg->GetXaxis(); > > axis->SetTitle("XTITLE"); > > > >But illegal pointer message again. > > > >How ever, I can make this with TGraph. > >Why? Isnt it true that TMultigraph is just related to TGraph? > >Could this be a bug? > > > > > >Thanks > > > >I used ROOT 3.05/05 gcc 3.3.3 Redhat 9.0 > > > > > > > > -- -------------------------------------------------------- Zaldy A. Nawang PS Users Room 2 Yon Gokan, E362, Neutrino Group, IPNS, KEK, Japan e-mail: zaldy@neutrino.kek.jp Tel. No. : (81) 029864 - 5387 --------------------------------------------------------
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