Re: TH1::FillError() function

From: Faouzi Attallah (attallah@clri6a.gsi.de)
Date: Wed Dec 02 1998 - 17:38:23 MET


Hi Rene,

On Wed, 2 Dec 1998, Rene Brun wrote:

> Faouzi Attallah wrote:
> > 
> > Hi Everybody
> > 
> > I would like to fill up a histogram (hf) with a user-weight-error,
> > such as
> >         hf->Fill(xval, xweight)  ;
> >         hf->FillError(xval, error) ;
> > 
> > The problem is my *vector(xval, xweight, error) is not sorted to
> > allow any use of TH1::SetBinContent()/SetBinError()
> > Any suggestion ..
> > 
> > Greetings,
>  
>  Hi Faouzi,
> The normal procedure to fill an histogram with weights and correct
> storage of the error bars is:
>    TH1F *hf = new TH1F("hf",...
>    hf->Sumw2();
>    hf->Fill(xval,xweight);
> 
> The error in bin I will be computed by taking sqrt((sum of xweight)^2)
> 
> Rene Brun
> 

You are right as long as its a statistical error, which is not my 
case where , e.g., 
	error = xweight/sqrt(n) ; 
n being the Number of averages in Schottky spectra.
Any other suggestion..

Greetings,
Faouzi



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