Hi Giacomo, TMarker doesn't know about log scale in pad. You should compute the Log10 yourself. Here is an example: { gROOT->Reset(); TCanvas *c1 = new TCanvas("c1","Test",0,0,600,600); c1->SetLogy(); fun1 = new TF1("fun1","10^x",1,3); fun1->SetFillColor(1); fun1->Draw("C"); TMarker *marker = new TMarker(2.,TMath::Log10(100.),21); marker->SetMarkerSize(4.); marker->Draw(); } Cheers, Olivier -- Org: CERN - European Laboratory for Particle Physics. Mail: 1211 Geneve 23 - Switzerland E-Mail: Olivier.Couet@cern.ch Phone: +41 22 7676522 WWW: http://cern.ch/Olivier.Couet/ Fax: +41 22 7677155 On Mon, 5 Aug 2002, Giacomo Bruno wrote: > Hi, > I would like to draw markers in a canvas where histos > in y-logarithmic scale are already drawn. > I tried with both the Draw and the DrawMarker method, but the > markers are drawn at wrong y-positions. I also tried to use NDC > coordinates without success. > Has anyone ever faced and solved this problem? > > Cheers > > Giacomo > > > > ----------------------------------------- > | Giacomo BRUNO | > | | > | CERN | > | EP Division | > | | > | mail: 40-2-B20 | > | C.E.R.N. | > | CH - 1211 Geneva 23 | > | Switzerland | > | e-mail: Giacomo.Bruno@cern.ch | > | phone: +41 22 76 71624 | > ----------------------------------------- > > > >
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