Partly solved [Fwd: Problem with 2D Fit and 2D Function]

Hi!

   I had forgotten a "rho" inside the TFunction. Now the plot of the Function func and the fit perfectly agree. Anyhow the fit still looks quite bad and the ChiSquare is really high.

Any help is welcome.
Have a nice day,
bye,
Francesca

• Original Message ---------------------------- Subject: Problem with 2D Fit and 2D Function From: francesca.belloni_at_ts.infn.it Date: Wed, November 9, 2011 1:51 pm To: roottalk_at_root.cern.ch

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Hi.
  I am trying to fit a 2D histogram with a 2D Gaussian function only on a certain range.

   When I fit the function everything seems to be fine (apart the fact that the fit is not at all great and the ChiSquare got by ROOT is totally different -about 350 times lower - from the ChiSquare calculated by implementing the mathematical formula).

   Anyhow, then I tried to reproduce the Fit by using a TFunction with the same parameters obtained by the Fit,but the image I get is totally different from the image obtained by plotting the Fit (in the attached picture, the graph plot as a net is the Fit, the coloured one is the function).

   In attachment is a short routine. Did I commit some mistakes, pls? Any help is really welcome.

Thank you,
regards,
bye,
Francesca

P.S.
I am running ROOT version 5.28.00g on Ubuntu 10.10. Received on Wed Nov 09 2011 - 14:33:09 CET