RE: [ROOT] user-defined function in Draw

From: Philippe Canal (pcanal@popserver1.fnal.gov)
Date: Tue Apr 08 2003 - 22:27:15 MEST 

Hi Martin,

   tree->Draw( "func(length)" );
 
should work (if and only if you use the TF1 constructor you mentioned).

Cheers,
Philippe

-----Original Message-----
From: owner-roottalk@pcroot.cern.ch
[mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of Martin Schroedter
Sent: Tuesday, April 08, 2003 3:13 PM
To: roottalk@pcroot.cern.ch
Subject: [ROOT] user-defined function in Draw


Hi,

can someone tell me how to apply a user-defined function to a leaf? 
Let's say I have data in a leaf called "length", then i can histogram 
the sqrt(length)
tree->Draw("sqrt(length)")

How can I use my own function instead of sqrt()? The obvious (to me) 
choice does not work:

TF1 func("func","1+2*x",2,6);
tree->Draw( "func.Eval(length)" );

*ERROR 26 :
  Unknown name : "func.Eval(length)"

Thank you,
	Martin

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