Re: [ROOT] How do you display the error matrix?

From: Rene Brun (Rene.Brun@cern.ch)
Date: Wed Dec 04 2002 - 22:32:43 MET


Hi Gail,

An example

{
   TH1F h("h","test",100,-2,2);
   h.FillRandom("gaus",1000);
   h.Fit("gaus");

   const int npar = 3; 
   TMatrixD matrix(npar,npar);
   gMinuit->mnemat(matrix.GetElements(),npar);
   matrix.Print();
   matrix.Draw("text");
}

Rene Brun

On Wed, 4 Dec 2002, Gail Ruby wrote:

> Dear Rooters,
> 
> I am running version 3.03/09 on a Linux maxhine.
> 
> After doing my fit using TF1::Fit:
> 
> root [15] TF1 *ff = new TF1("ff", "gaus+pol3(3)", 1.78, 1.95)
> root [16] ff->SetParameters(hsD0Mass1->GetMaximum(), 1.862, 0.006, 1, 1,1, 1)                
> root [17] hsD0Mass1->Fit("ff")                                                                
> 
> 
> I typed in the following:
> 
> root [18] const int npar =7; doublematrix[npar][npar];  gMinuit->mnemat(&matrix[0][0],npar);
> root [19] 
> 
> The return provided nothing.
> 
> How do I get a display on the screen of the error matrix?
> 
> Thanks,
> Gail Ruby
> 



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