Rene, yes, itmust. So why is the binning not automatically taken over? Thomas. Rene Brun wrote: > Thomas, > > The resulting histogram must have the same number of bins than the > operand histograms. > > Rene Brun > > On Thu, 18 Mar 2004, Thomas Bretz wrote: > > >>Hi Rene, >> >>why does h4 need the same number of bins? It is enough if h4 'takes' the >>binning from either h3 or h2, isn't it? >> >>Thomas. >> >>Rene Brun wrote: >> >>>Your two projections h2 and h3 have the same number of bins, >>>eg you can do h3->Divide(h2); >>>However, you call the default constructor for h4. h4 does not have the >>>same number of bins as h2 and h3. >>>Instead of >>> TH2D *h4 = new TH2D; >>> h4->Divide(h3, h2); >>>do >>> TH2D *h4 = (TH2D*)h2->Clone(); >>> h4->Divide(h3, h2); >>> >>>Rene Brun >>> >>>Thomas Bretz wrote: >>> >>> >>>>Hi, >>>> >>>>I have a >>>>Double_t x[5] = { 0, 1, 2, 3, 4 }; >>>>TH3D fHist("", "", 4, x, 4, x, 4, x); >>>>and do: >>>>fHist.GetZaxis()->SetRange(3, 4); >>>>TH1 *h2 = fHist.Project3D("xy_off"); //, -1, 9999, "E"); >>>> >>>>fHist.GetZaxis()->SetRange(1,2); >>>>TH1 *h3 = fHist.Project3D("xy_on"); //, -1, 9999, "E"); >>>> >>>>TH2D *h4 = new TH2D; >>>>h4->Divide(h3, h2); >>>> >>>>And I get >>>>Attempt to divide histograms with different number of bins... >>>> >>>>What am I doing wrong? I would expect to have two projections to have >>>>the same binning... >>>> >>>>Thomas. >>> >>> > >
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