Minuit in a loop

ROOT
1

Hi,

I am trying to fit with minuit different histogram within a loop.
The problem is that I get the same values for the parameters all the times
for each different histogram (and it’s wrong) while if I fit an histogram one at the time I get different values;

here it is my pseudo-code


for (int ex=0; ex<1000; ex++){

 TH1F *data = getHisto(ex);

    fillVectorFromHisto(data);

// ...
// ...

    TVirtualFitter::SetDefaultFitter("Minuit");
    TVirtualFitter* minuit = TVirtualFitter::Fitter(0,21);

    char pname[6];

    minuit->SetParameter(0,"Lumi" ,L, 0.0001,0,0);
    
  for (int i = 1; i < 21; ++i) {

      sprintf(pname,"par%d",i);
      minuit->SetParameter(i, pname,0,0.01, 0,0);

  }

  minuit->SetFCN(fcn);


 // minimize
  minuit->ExecuteCommand("MIGRAD",arglist,2);

// here I got values of the parameter each time the same


}

I am sure that I am fitting different histograms
I tryed to define TVirtualFitter* minuit = TVirtualFitter::Fitter(0,21);
outside the loop but it doesn’t work

thank you
Francesco

2

sorry, solved… my fault
I haven’t correctly initialized a vector

you can delete this tread.

Francesco