Hi, In addition to Yannick answer, you may use the following : { Double_t par(np) ; // np = nbre of parameters Double_t erpar(np) ; // the error vector Int_t i ; fct = new TF1("xxx",txt, fmin, fmax); //xxx = fonction fct->GetParameters(par); // extract the param. values chi2 = fct->GetChisquare() ; // extract the chi2 for (i=0 ; i < np; i++) // extract the param. error values fct->GetParameters(&erpar[i]); } Let me know if you need something else about this topic. Faouzi F. Attallah GSI mbH Planckstr 1 D-64291 Darmstadt Tel: +49 (0)6159 71 2743 Fax: +49 (0)6159 71 2901 Email: F.Attallah@gsi.de On Mon, 5 Jul 1999, Patois Yannick wrote: > Hello, > > You can have a look on the exemple "multifit.C" > http://root.cern.ch/root/html/examples/multifit.C.html > > Look at the lines : > > g1->GetParameters(&par[0]); > g2->GetParameters(&par[3]); > g3->GetParameters(&par[6]); > > look at GetParameter and GetParameters in > http://root..cern.ch/root/html/TFormula.h. > > Double_t TFormula::GetParameter(Int_t ipar) will let you get one > parameter, eg : > Double_t mean = fit->GetParameter(1); > > And void GetParameters(Double_t* params) will gives you every parameter in > an array. > > Hope it helps, > > Yannick > > _/ Yannick Patois \_________________ Address (home) __________________ > | irc(undernet): Garp on #france25+ | La Villa des Sciences | > | email : patois@ganil.fr | 12, avenue de Cambridge | > | web :http://www.sura.org/~patois/ | 14200 Herouville-Saint-Clair | > | Tel(home) :+33 02 31 94 50 32 | FRANCE | > |___________________________________|__________________________________| > > On Mon, 5 Jul 1999, Stephen Markacs wrote: > > > > > How do I get the mean and sigma from a fit? I know it prints them to the > > root session, but I want to actually get at them within my code so I can > > put them on my plot. > > > > Thanks. > > > > S t e p h e n M a r k a c s > > stephen@phys.columbia.edu > > http://phys.columbia.edu/~stephen/ > > > > > > >
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