Re: [ROOT] using LoadTree with a TChain

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Jan 08 2002 - 15:58:27 MET


Ken,

As I said, MakeClass is correct in 3.02/06.
This was a problem in 3.01

Rene Brun

Ken Bloom wrote:
> 
> On Mon, 7 Jan 2002, Rene Brun wrote:
> 
> > Hi Ken,
> > The code generated by MakeClass is correct.
> > The statement:
> >      Int_t ientry = LoadTree(jentry);
> > is not necessary if you do not need the entry number in the current Tree.
> > The statements
> >     fChain->GetEntry(jentry)
> > and
> >     fChain->GetEntry(ientry)
> >
> > will give identical results for the first file, but for subsequent
> > files, only the first statement will give the correct result.
> >
> > I assume that you use the pro version 3.02/06
> 
>         I'm afraid that I disagree -- I believe that the "jentry" argument
> gives the wrong result after the first file, and the "ientry" argument gives
> the right answer for all the files in the chain.  If I use "jentry", I find
> that I get the first file just fine, but once jentry becomes sufficiently
> large that I have moved past the the first file, then I keep getting the final
> event of the first file over and over again.  If it would be useful, I can try
> to reproduce this with some small ntuples, although as far as I'm concerned I
> have now solved my problem and I would rather move on to other things.  I am
> using version 3.01/06, which is the latest that we've got at CDF.  Thanks,
> best wishes.
> 
>                                                 Ken
> 
> ------------------------------------------------------------------------------
> Ken Bloom, Karma Adjuster                                Department of Physics
> 734-763-2329 / 734-936-1817 (fax)                       University of Michigan
> kenbloom@umich.edu                              http://www.umich.edu/~kenbloom



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