I have two problems with RooFit and MINUIT2, and despite extensive searching, I haven’t been able to find solutions. I would greatly appreciate any help or guidance on these issues.

  1. The RooFitResult class in RooFit has a status() method that returns a MINUIT status code according to the ROOT Reference Guide. I would like to understand the meaning and interpretation of this status code. Could someone provide more information about that?

  2. I have encountered several flags in the output from MINUIT, as shown in the example image below:

I have been unable to find detailed descriptions or explanations for these flags. I would greatly appreciate it if someone could provide me with the meanings or interpretations of these flags.

Thank you in advance.

ROOT Version: 6.26
Platform: ubuntu 22.04
Compiler: gcc version 11.3.0

Hi @lukroz,

welcome back at the forum. Maybe @Jonas could give you a hand here?


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The meaning of these values are:

  • MINIMIZE: minimization status and the meaning is explained here
  • HESSE : covariance matrix status and more information is here.

You can also increase the print level in the minimization to understand better what is happening. You can do this by adding RooFit::PrintLevel(1) to the fitTo command in RooFit.