Hi Aaron, Sorry for the long delay to answer this mail. I did not see your original mail. If instead of: aP2D->ProjectionX("prox",20,20)->Draw(); you do: aP2D->ProjectionX("prox",20,20)->Draw("e"); you will see the error bars. If instead of; aP2D->ProjectionX("prox",20,21)->Draw(); you do: aP2D->ProFileX("prox",20,21)->Draw(); you will obtain what you required for your second option. Rene Brun > Rooters, > > Lately I've been using the very useful TProfile2D type of histogram, > and would find it very convenient to be able to use Profiles of these > histograms. > However, projections of TProfile2D's do not behave in the expected way. (I'm > using 3.05.02 on Linux) > > Using the example below, a Projection of just one bin has the values > from > that bin, but no errors. It would be nice to have the errors displayed. > > Next, when projecting over more than one bin, one gets the sum of > the > bins included. Given that it is a Profile histogram, it would make more > sense > to get the average, with the errors calculated in the same way as the > original > Profile histogram. > > regards, > Aaron Roodman > > TProfile2D* aP2D = new TProfile2D("aP2D","test > Profile",40,-4.,4.,40,-4.,4.); > for > (Int_ti=0;i<10000;i++){aP2D->Fill(gRandom->Gaus(),gRandom->Gaus(),gRandom-> > Gaus());} > aP2D->ProjectionX("prox",20,20)->Draw(); > aP2D->ProjectionX("prox",20,21)->Draw(); >
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