Minuit STATUS=RESET and Unfixing Parameters


I’m trying to do a fit with some parameters fixed and then to unfix those parameters while fixing some that had been previously unfixed. The first fit goes fine and then I fix some parameters with TFitter::FixParameter and attempt to unfix other parameters using TFitter::SetParameter. When I make each call to TFitter::SetParameter Minuit prints out something like:

MINUIT WARNING IN PARAM DEF                                                                                                                           
============== REDEFINING A FIXED PARAMETER.                                                                                                          
                   PARAMETER   51  p50 RESTORED TO VARIABLE.                                                                                           
    51 p50          1.15012e+04  1.28255e+03     no limits               

This sounds like what I want to do (to restore a fixed parameter to a variable one). The problem comes when I then try to do the second fit. If I call TFitter::ExecuteCommand(“SIMPLEX”,0,0) and TFitter::ExecuteCommand(“MIGRAD”,0,0) then the only output that I get (with verbose settings) is:

**  636 **SIMPLEX                                                                                                                                     
**  637 **MIGRAD                                                                                                                                      

None of the parameters change at all and the status in TMinuit::fCstatu is RESET. It doesn’t even call the function to minimize at all (tested using debug statements). I tried calling TMinuit::mnrset(1) to see if this might let Minuit know that the settings have changed and it needs to do more but it has no effect.

Does anybody have any idea what’s going on here? Thanks!


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