Re: [ROOT] TGraphAsymmErrors()

From: Rene Brun (brun@pcbrun.cern.ch)
Date: Mon Jul 19 2004 - 21:40:57 MEST


Alexander,
  -send the shortest possible script reproducing your problem
  -indicate which ROOT version you use

Rene Brun

On Mon, 19 
Jul 2004, Alexander Wagner wrote:

> Hi!
> 
> Just a  short  question:  Consider  a  dataset  which  looks
> somewhat like this:
> 
> 409.00000    0.2875184   0.0251621804162307
> 421.00000    1.08303395   0.0488355952731649
> [...]
> 
> That is x-value, y-value and the error estimated.  Now  this
> error is symmetric, but I wrote  some  general  function  to
> plot errors which uses TGraphAsymErrors(). Just setting xlow
> and xhigh to the same value.
> 
> It seems root doesn't like my data.  Especially not the  0.x
> errors.  I get a fine plot of the data  line  but  no  error
> bars.  Now if I multiply this two colums by  a  constant  so
> that the errors are .gt. 1 I get nice error bars. Did I miss
> something in the docs or is it intended for the error-graphs
> to deal only with errors .gt. 1?
> 
> Well I solve my problem just by multiplication which is in a
> way ok with me at the moment.  Maybe I made a  dumb  mistake
> somewhere?
> 
> 



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