[ROOT] TF1 and errors

From: Michael Wiesmann (wiesmann@e18.physik.tu-muenchen.de)
Date: Thu Jun 05 2003 - 19:58:12 MEST


Dear Rooters!

I have fitted a TH2F with a TF2 function (14 parameters). Now I want
to calculate the value in a bin(cell) (btw, why are there functions
TF2::SetCellContent(),TF2::SetBinContent(), which absolutely do the
same?) with resulting error from the fit, including covariances.

I found a function TF1::Eval(x,y,z,t) which gives a value, but I could
not find something connected to errors. (btw, what is "t")

In the digest from Wed Dec 04 2002 - 22:32:43 MET I found a way to get
the cov matrix. via TMinuit::mnemat(..), thus with the knowledge of
the Hesse matrix at this cell one should be able to compute an error
(unoftunately neither TMinuit::mnhess() nor TMinut::mnhes1() do not
have any return value) ...


Does anybody have an example how to do this?


Thanks a lot,

Michael



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