Hi Stanislav, See my answer on this subject at: http://root.cern.ch/root/roottalk/roottalk03/5107.html Rene Brun Stanislav Nesterov wrote: > > Hi Alexander, > You are right in this case - if you look at TH1::Fit() code you'll see > such lines: > > // - Set error criterion for chisquare or likelihood methods > // - MINUIT ERRDEF should not be set to 0.5 in case of loglikelihood fit. > // - because the FCN is already multiplied by 2 in H1FitLikelihood > // - if Hoption.User is specified, assume that the user has already set > // - his minimization function via SetFCN. > arglist[0] = 1; > if (Foption.Like) { > hFitter->SetFitMethod("H1FitLikelihood"); > } else { > if (!Foption.User) hFitter->SetFitMethod("H1FitChisquare"); > } > hFitter->ExecuteCommand("SET ERR",arglist,1); /// > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > So your efforts in setting MINUIT ERRDEF was for nothing. Sorry. I > see the only solution is not to use the TH1::Fit() method or change the > method itself > > Best regards, > > Stanislav. > > Alexander Dietz wrote: > > >Hi, > > > >to change the ERRDEF-parameter in MINUIT I tried the following: > > > > Double_t arglist[100]; > > > > TH1F* h1=new TH1F("h1","h1",3,1,4); > > h1->Fill(1,1); > > h1->Fill(2,2); > > h1->Fill(3,1); > > h1->Draw(); > > > > TVirtualFitter *hFitter = TVirtualFitter::Fitter(h1); > > h1->Fit("pol0"); // Fit 1 > > > > arglist[0]=1; > > hFitter->ExecuteCommand("SET ERR",arglist,0.7); > > gMinuit->SetErrorDef(0.7); > > h1->Fit("pol0"); // Fit 2 > > > > > >But both fits gave the same errors! > >So how to change the ERRDEF -parameter? > > > >Alexander Dietz > > > >
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