plotting user functions

From: Wouter Hulsbergen (s37@nikhef.nl)
Date: Tue Jul 01 1997 - 09:54:22 MEST


Dear ROOT people,

I have written the following code

  {
  #include <math.h>

  float distribution(float pt, float pbar)
  {
    float pzbar = sqrt(pbar*pbar-pt*pt) ;
    float Norm = 1. ;
    return (pbar*pt/2* (pbar*pzbar + pt*pt*log(pbar+pzbar)) 
      - pt/3 * pzbar*pzbar*pzbar - pt*pt*pt * pzbar) /Norm ;
  };

  int main()
  {
    float pbar = 4. ;
    TF1 func("func","distribution(x,pbar)",0,pbar) ;
    func.Draw();
  }
  }

which I want to use to plot the `distribution' function, using
  root> .L distrib.C ;
  root> main();

However, this doesn't work because 
    Unknown name : "distribution(x,pbar)"
although the function `distribution' is known. Can I use user
defined functions in a TF1 or TFormula definition?
Regards, Wouter.



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