Strange behavior in TAxis->SetRange()


I am having trouble getting this function to behave as expected. Short summary: SetRange(2,2) grabs data from bins 2 and 3. I checked this by simultaneously filling an ntuple and using nt->Draw() with the cuts that I expected to implement using SetRange(). Now for the details.

I have filled an ntuple and a 3D histogram in the same block of code:

TFile* myfile = new TFile("electron_merged.root","RECREATE");
TH3* epeak = new TH3F("epeak0","R vs p_{Track} / E_{tower} Vs. Eta",40,-1.,1.,200,0.,10.,10,0.,0.03);
TNtuple* ntup = new TNtuple("nt","","p:energy:r");


     epeak->Fill(eta, p/energy, r);

so if I open electron_merged.root in an interactive session and call


the two plots should show up on top of each other. However, it turns out that the histogram projection is getting data from the first two r bins. The ntuple plot that matches the histogram plot is this one (note the different cut):


Is this a known problem? You can find electron_merged.root at

Note: to see the plots line up exactly, use the “final” key instead of the “energy” key in the ntuple. Thanks,

Adam Kocoloski

by the way, the file was created and read with v5.08. Thanks, Adam