Jan, By default, errors are computed as sqrt(bin content). If you want TH1::Scale to take into account the errors, the errors must exist. Do h->Sumw2(); h->Scale(normFac); Rene Brun Jan Malinowski wrote: > > Hello Rooters, > > I have rescaled a histogram. I used TH1::Scale( Double_t ) method: > h->Scale( norFac ); > > I received strange errors, e.g.: > x-center dN/dEsec err-dN/dEs > 11.22 7.2651e-007 8.5235e-004 > 14.13 4.6631e-007 6.8287e-004 > ----------- > When I made the same (I suppose) with: > Float_t cbin =h->GetBinContent( ib ); > Float_t error=h->GetBinError( ib ); > hO->SetBinContent( ib, (cbin*cScal) ); > hOl->SetBinError( ib, (error*cScal) ); > > I received following results: > x-center dN/dEsec err-dN/dEs > 11.22 7.2651e-007 1.5226e-008 > 14.13 4.6631e-007 1.2199e-008 > ------------ > Why is there such difference in the results? > > Janek.
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