[ROOT] TMultiGraph error in connection with GetAxis

From: Michael T. Gericke (mgericke@leneut.lanl.gov)
Date: Sun Mar 02 2003 - 05:48:59 MET 

Hi ROOTers,

I am using the TMultiGraph Class in the following way:

  TMultiGraph *mg = new TMultiGraph();
  mg->SetTitle("Lock-In Amplifier Technique Signals");
  mg->GetXaxis()->SetTitle("ms");
  mg->Add(gr1);
  mg->Add(gr2);
  mg->Add(gr3);
  mg->Draw("ALP");


When I run my file on the root command line, I get the
following error:

Error: illegal pointer to class object GetXaxis() 0x0 138  
FILE:Rot_Src_Scope_Out.C LINE:107

I know that this refers to the line "mg->GetXaxis()->SetTitle("bla")",
because if I remove it the error doesn't come up.

Does anyone know how to set the axis titles for a TMultiGraph?

Thanks,

Michael Gericke

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