Errors for bins with Negative Sumw

From: Hovhannes Khandanyan <khandan_at_cern.ch>
Date: Tue, 26 Oct 2010 19:24:19 +0200

      Dear ROOTers,

In my analysis I have a histo h1 some of bins of which have negative fSumw (eg. bin=53):
...........

  fSumw[51]=6.865, x=1010
  fSumw[52]=0, x=1030
  fSumw[53]=-0.985, x=1050
  fSumw[54]=4.868, x=1070
  fSumw[55]=5.815, x=1090
  ................

Further, I Clone() this histo to h2 which I need to h2->Scale() after having done h2->Sumw2(). Anyhow, when I do h2->IntegralAndError (...) I get 'nan' for the error. This I think is due to the fact the errors are not computed for bins with negative fSumw:

...............

  fSumw[51]=6.865, x=1010, error=2.62011
  fSumw[52]=0, x=1030, error=0
  fSumw[53]=-0.985, x=1050, error=nan
  fSumw[54]=4.868, x=1070, error=2.20635
  fSumw[55]=5.815, x=1090, error=2.41143
.................

So, please let me know if there is a work around this problem, so that I can get IntergalAndError() machinery running also for this particular case.

Thank you,
Hovhannes Received on Tue Oct 26 2010 - 19:24:55 CEST