TTreeFormula

From: nigel@kiwi.chm.bnl.gov
Date: Mon Oct 11 1999 - 23:23:50 MEST


Dear RootTalk,
	      I have a ntuple, called ntuple,with columns "run:noise"

I make a TTreeFormula via

 TTreeFormula *h=new TTreeFormula("h","run<1000",ntuple)

then when I go

ntuple->Draw("run","h")

I get 
*ERROR 26 : 
 Unknown name : "h"

when I try

ntuple->Draw("run","h")
I get
Error: Can't call TNtuple::Draw() in current scope
FILE:/tmp/fileH9aDTt_cint LINE:1

Clearly I am missing the point about TTreeFormula.
Although this simple example could have been performed
with a TCut, or even string, I would like to know
how to use TTreeFormula in general, so when I have a complicated
formula I can apply it to the ntuple as a cut.

I tried to find an example, but could not. Could someone
help me out.

Thanks
Nigel 



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