[ROOT] TTree::Draw strange behavior ?

From: Alberto Baldisseri (a.baldisseri@cea.fr)
Date: Thu May 11 2000 - 20:44:01 MEST 

Hi rooters,
    I like to use a TTree filled with a TClonesArray with the splitlevel
= 1 option. Like in the macro
tcl.C delivered with the ROOT distributions 2.24/04. I type :

root [0]> tcl.C(1)

to build the file tcl.root containing the TTree T. I found the following
behavior :

1) T.Draw("fX1[20]") and T.Draw("fX1[20]","tcl_>20") don't give the same
result !
In other words, the protection tcl_>20 against spurious data is
MANDATORY, since
plotting the 21th member of a table fX1[20] have no sense for events
with tcl_<=20.
There is a plan in ROOT to improve that and to avoid to put explicitly
the condition
tcl_>20 ? There is a technical problem around ? Since ROOT knows for
each event
how long is the table (variable tcl_) ?

2) Another problem related araises when I put some other condition :

T.Draw("fX1[20]","abs(fX1[20]-0.1)<0.3&&tcl_>20") and
T.Draw("fX1[20]","tcl_>20&&abs(fX1[20]-0.1)<0.3") dont give the same
result !

I suspect (looking to some data of my experiment) that the good one is
the first.

Anybody observe before those things ? Is all that normal ?

Regards,

Alberto


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