Thanks. This works, but one problem is that if I decide to change the 
y-scale then any other things I changed in the graph (for example an arrow 
that I added) are deleted/reset.
I added // *MENU* after the declaration of the function SetLimits in 
hist/inc/TAxis.h and recompiled the source. Now SetLimits shows up in the 
pop-up menu for the y-axis. Using this I can change the y-scale as I want. 
But perhaps there are reasons not to do this. Is this bad practice?
Hajo.
>From: Rene Brun <Rene.Brun_at_cern.ch>
>To: Hajo Molegraaf <hjausenet_at_hotmail.com>
>CC: roottalk_at_pcroot.cern.ch
>Subject: Re: [ROOT] problem with y-scale (a bug?)
>Date: Thu, 19 Jan 2006 21:03:13 +0100 (MET)
>
>When using the TreeViewer you can set the histogram binning in
>the "Histogram" box in the top bar. In your case you can set
>   htemp(30,0,300,100,1,1e5)
>
>Then click on the Draw button
>
>Rene Brun
>
>On Thu, 19 Jan 2006, Hajo Molegraaf wrote:
>
>>Hi,
>>
>>I like the TreeViewer for TNtuples that can be lanched from the TBrowser, 
>>but the y-range of a plot can not be set properly using the GUI.
>>
>>With the following script I create a root file
>>
>>//************************
>>{
>>  TFile* file = new TFile("test.root","RECREATE");
>>  TNtuple* data = new TNtuple("data","","Temperature:Resistance");
>>  double T, R;
>>  for( T = 10.0; T < 300.0; T += 1.0 )
>>  {
>>      R = T*T;
>>      data->Fill(T,R);
>>  }
>>
>>  file->Write();
>>  file->Close();
>>}
>>//*************************
>>
>>I can open this root file in the TBrowser and I can view the TNtuple with 
>>the TreeViewer. I drag the Temperature branch to X and the Resistance 
>>branch to Y and I click on the button to draw the graph. This creates a 
>>nice graph, but I want to have a logaritmic y-scale. So I click on the 
>>canvas and choose SetLogy. This changes the y-scale from around 2.5e3 to 
>>1e5. Well, I want to see all the data, so I click on the y-axis and select 
>>SetRangeUser. I fill in 10 for ufirst and 1e7 for ulast. This changes the 
>>y-range from 3e5 to 1e7.
>>
>>How can I change the y-range? I know I can do it with a script using 
>>SetLimits, but it seems that using only the GUI it does not work properly. 
>>Is it not possible to use SetRangeUser for this? Why does it respond so 
>>strange?
>>
>>By the way, is it an idea to add SetLimits to the popup menu for the axis 
>>by adding '// *MENU*' to the function SetLimits in include/TAxis.h ?
>>
>>I'm using ROOT Version   5.09/01  16 December 2005, Compiled for linux 
>>after downloading the CVS version.
>>
>>Thanks,
>>Hajo Molegraaf
>>
>>_________________________________________________________________
>>Nieuw op MSN Messenger 7.5: Dynamische achtergronden 
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>>
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