The macro below demonstrates the problem that I have been having with ntuples. When I run the macro on my machine (Linux 2.0.36, 2.21.08) I get a histogram displayed with the ranges going from -21 to -15. However, according to GetMaximum and GetMinimum, the X range should really be from -20.5 to 20.5. Why is the X axis set up incorrectly? Interestingly, if I change nsamples to a smaller number, say 21, everything works as expected. Thanks for your help. Glen { gROOT->Reset(); TNtuple *n = new TNtuple("ntuple","RSphere attachment data", "xs:ys:zs:xe:ye:ze"); Float_t xs, ys, zs; Float_t start, delt=1.; Int_t nsamples = 41; start = -nsamples*delt/2.; for (Int_t i=0; i<nsamples+1; i++) { for (Int_t j=0; j<nsamples+1; j++) { for (Int_t k=0; k<nsamples+1; k++) { xs = start + i*delt; ys = start + j*delt; zs = start + k*delt; n->Fill(xs,ys,zs,i,j,k); } } } printf("min = %f\n",n->GetMinimum("xs")); printf("max = %f\n",n->GetMaximum("xs")); n->Draw("xs"); } ********************************************************************* Glen R. Salo g.r.salo@ieee.org Mission Research Corporation (937)429-9261 Ext. 119 3975 Research Boulevard (937)429-2625 Fax Dayton, Ohio 45430-2108 *********************************************************************
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