Change Minuit algorithm when fiting histogram

Roofit and RooStats
1

Hi Experts,

is it possible to change between algorithms when fitting a histogram? Something like this:

#include "TH1F.h"
#include "TF1.h"

Double_t fitFunc (Double_t*x, Double_t*par)
{
    return par[0]+par[1]*x[0];
}

void testMin(void)
{

    TH1F h("h","h",10,0,10);
    for (int i = 1; i != 11; ++i) {
    for (int j = 0; j != i; ++j) {
        h.Fill(i);
    }
    }

    TF1 * f1 = new TF1("f1", fitFunc,0.,1000.,2);
    f1->SetParameter(0, 1.);
    f1->SetParameter(1, 0.);

    Int_t r = h.Fit("f1","MER");

    if (r != 0) {

        // CHANGE fit algorithm to (e.g.) SEEK ??

        h.Fit("f1","MER");// perform fit using minuit+new algorithm
    }

    delete f1;
}

I tried ROOT::Math::MinimizerOptions::SetMinimizerAlgorithm(const char*) but requires an object.

TVirtualFitter don’t have a call to this function either.

Thanks in advance

2

For available TH1::Fit options see http://root.cern.ch/root/html/TH1.html#TH1:Fit@1
See the section “Access to the Minimizer information during fitting” therein.

See also the source code from the bottom of (from the “Creating a Minimizer via the Plug-In Manager” section): http://root.cern.ch/drupal/content/numerical-minimization

3

Thanks for the info.