How to Draw a function of ntuple variables ?

From: Patois Yannick (patois@ganil.fr)
Date: Tue Jul 06 1999 - 10:51:07 MEST 

Hello,

I can draw a ntuple, like :

my_ntuple->Draw("var1:var2");

I can use simple predefined functions :

my_ntuple->Draw("sqrt(var1):var2");

But if I want to define my own function, using many variables in the
ntuple, I would say something like in paw one can do :
nt/plot 1000.toto.f(5)

Where toto.f can then use any of the ntuple varable to create it's return
value, using the defined COMMONs.

I tryed something like :

Float_t xrms(Float_t *PMT)
{
  return(*PMT);
}

void rms()
{
  TF1 *xrms = new TF1("xrms",xrms,0,1000,1);
  Tournesol->Draw("xrms(QDCf1)");
}

But it did'nt worked at all. Of course it's still far from what I would
like to have (a function with *every* ntuple vars for this event as
input).

Any clue ?

	Yannick


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