Re: [ROOT] User defined function as a weight.

From: Rene Brun (Rene.Brun@cern.ch)
Date: Wed Aug 06 2003 - 10:41:56 MEST


Hi

Using 3.05/07, create a file w.C as below

//file w.C
double w(double z, double d, double sig) {
   double s2 = sqrt(2)*sig;
   return 0.5*(TMath::Erf((z+d)/s2-TMath::Erf((z-d)/s2));
}

then in ROOT, do

root > .L w.C
root > ntuple.Draw("el11","(z>0)*w(z1m,10,5)");

Rene Brun



On Wed, 6 Aug 
2003, Dmitry A. 
Shtol wrote:

> I asked this question some time before, but didn't get answer. I need 
> to use user defined function as a weight in TNtuple::Draw(). In PAW it 
> looks like that:
> 
> app comis quit
>     real function w(z,d,sig)
>     real z,d,sig,s2
>     s2=sqrt(2.)*sig
>     w=0.5*(erf((z+d)/s2)-erf((z-d)/s2))
>     end
> quit
> 
> *************
> 
> nt/pro [id] [idn] el11 [cond]*w(z1m,10.,5.)
> 
> Where el11 and z1m are elements of ntuple.
> What is the simplest way to do it in ROOT?
> 
> ==============================================================
> Dmitry A. Shtol                        (SND group)
> Budker Institute of Nuclear Physics
> 



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