Hi Giuseppe, before invoking GetXaxis() you should Draw() the Graph: On Mon, 8 Jan 2001 Giuseppe.LoRe@ct.infn.it wrote: > > Hi, i have a little problem with TGraph. > How can i put a title to an axis? > I try with ...->GetXaxis()->SetTitle("..") but i obtain > Error: illegal pointer to class object GetXaxis() 0x0 122. > TGraph *mltplct_gr1 = new TGraph(12, Zv, z1); mltplct_gr1->SetLineColor(2); mltplct_gr1->SetLineWidth(2); mltplct_gr1->SetMarkerColor(4); mltplct_gr1->SetMarkerStyle(21); mltplct_gr1->Draw("ACP"); //<<<<<<<<<<<<<<< mltplct_gr1->GetXaxis()->SetTitle("Zv"); gPad->Modified(kTRUE); mltplct_gr1->SetTitle("Moltiplicity versus primary vertex position\n"); > Best regards, Otto > Dr. Otto Schaile Sektion Physik, LMU Muenchen Phone: +49 89 289 14070 Am Coulombwall 1, D-85748 Garching, Germany GSM: +49 171 4312031 FAX: +49 89 289 14072 EMail: Otto.Schaile@Physik.Uni-Muenchen.DE
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