[ROOT] Different TH2 projection errors in ROOT and PAW

From: Stanislav NESTEROV (Stanislav.Nesterov@cern.ch)
Date: Tue Sep 10 2002 - 13:07:37 MEST


    Hi, Rene,
    Again about PAW and ROOT compatibility...
    Recently I made some projections of 2d-histogramms, and noticed that 
in case of 2d-histogram with errors projected histograms in ROOT and PAW 
have different errors. I think PAW makes error calculation in this 
case more correctly than ROOT: ROOT actually calculates error bars without 
any respect to errors in original 2d-histogramm.

   Projection in PAW made by:
    PAW >  prox 8399
    PAW >  hi/proj 8399
    PAW >  hi/pl   8399.prox

   Projection in ROOT made by:

    root [1]  h8399->ProjectionX("_px",-1,-1,"e");
    root [2]  h8399_px->Draw();
   
   May be important: I've used 2d-histograms with errs, produced via HBOOK 
package, then convert them into ROOT file by means of h2root utility. But 
I've checked the code of H2ROOT and there're lines that convert 2d-errors 
from PAW to ROOT...

(ROOT-3.03/08 AFS-version for 7.2 redhat)

			Best regards,
					Stanislav.



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