Hi John, I agree with your comments. I have extended TVirtualFitter (now in CVS), adding two new functions Double_t* GetCovarianceMatrix Double_t GetParameter(int ipar) Rene Brun On Wed, 6 Aug 2003, Dr. John Krane wrote: > Hi, > > I'm trying to get the final fit parameter values and the covariance > matrix out of TVirtualFitter or TFitter. Is there no way to do this? > > I see > > Int_t GetParameter(Int_t ipar,char *parname,Double_t &value,Double_t > &verr,Double_t &vlow, Double_t &vhigh) > > ...but this looks like a cut'n'paste of SetParameter. Why would I have > to provide the initial values just to get the current one?! Should this > not be > > Double_t GetParameter(Int_t ipar) > > ...with a simple inline implementation? There also appears to be *no > way* to get the covariance matrix. Perhaps I should have bypassed > TVirtualFitter entirely and just used TMinuit directly. This course > seemed unwise to me at first, or at least non-aesthetic, but > TVirtualFitter seems to lack even the basic functionality I need. > > If I am wrong, could somebody please tell me how to (for instance) > modify the code of > > http://root.cern.ch/cgi-bin/print_hit_bold.pl/root/html/examples/minexam.cxx.html > > to get the parameters and covariance matrix with high-precision? I am > looking for something similar to mnemat for the latter. > > - John >
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