Hi Michael,
I think you have to draw the multigraph once, before calling GetAxis().
It should work as for a TGraph, for which the axis is created after that
you draw the graph.
Cheers,
Federico
On Sat, 1 Mar 2003, Michael T. Gericke wrote:
>
> 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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Federico Roncarolo federico.roncarolo@cern.ch
alchemist@infinito.it
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