Hi Tommaso, At filling time, ROOT increments the necessary statistics quantity in such a way that you can get the Covariance or correlation factor from these quantities by default. Only in case you call these functions on a subset of the bin range, the information is recomputed from the bin content. Rene Brun On Tue, 25 Nov 2003, Tommaso Chiarusi wrote: > Dear Rooters > > a question concerning the TH2::GetCovariance() method. > > The value retrieved of the covariance looks to be > bin independent, but the GetCovariance() > method gets the values of the various stats[7] elements (by means of > the TH2::GetStats() )in a bin-dependent > mode (in particular the x and the y value: they are the > center-bin values). > > It looks like that a TH2 remembers the exact x,y coordinates of the data > sample it is filled with, even though the data are shown 2D-binned. > > The same occurs for the Correlation Factor. > > > what I'm missing? > > > > Cheers, Tommaso > > >
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