Covariance from a fit to a double

ROOT
2

Hello

I will need the covariance matrix for my analysis the next week, so I was also interested in this issue.

I think there are several ways:

Retrieving it from gMinuit
root.cern.ch/root/roottalk/roottalk02/0387.html

From TFitResultPtr, using "TMatrixDSym cov = r->GetCovarianceMatrix(); " (or "TVirtualFitter::GetFitter()->GetCovarianceMatrix(); " for ROOT5)
Help in retrieving covariance matrix
Accessing Covariance Matrix from TFractionFitter
root.cern.ch/root/roottalk/roottalk07/0153.html

from Rene Brun and Eddy Offermann
How to get correlation matrix for fit?

Greetings