Re: [ROOT] Changing the ERRDEF parameter in MINUIT

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri Nov 21 2003 - 11:18:42 MET 

Hi Alexander,

If you use TMinuit directly, you can call TMinuit::mnexcm. eg
  int ierr=0;
  double arglist[1] = {2}; //for 2 sigma
  minuit.mnexcm("SET ERR",arglist,1,ierr);

If you go via the TVirtualFitter interface, see an example in the code of
TH1::Fit at http://root.cern.ch/root/htmldoc/src/TH1.cxx.html#TH1:Fit
search for "SET ERR"

Note that TMinuit has a function TMinuit::Contour drawing the n-sigma
contours. See:
  http://root.cern.ch/root/htmldoc/TMinuit.html#TMinuit:Contour

Rene Brun

Alexander Dietz wrote:
> 
> Hi Rotters,
> 
> how can I change the ERRDEF-parameter in TMINUIT to obtain different
> error-intervals (2 sigma, 3 sigma)?
> 
> Thanks for help,
> Alexander Dietz

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