FitSlicesY: per slice initial parameters

ROOT
1

Hi,

Slices in my 2D histogram can be fitted by a universal function, but require individual initial values and limits for each slice for the fit to converge. How can they be passed to FitSlicesY?

In my case, I need to know and use for that purpose some characteristics of the 1D histogram representing each slice, e.g. its mean and height in the middle.

2

Hi,

you can set the initial parameters of the function for all the slices. If you need different parameters for each slice to fit, you can then call many times
TH2::FitSliceY changing firstxbin and lastxbin and if needed merge the histograms with the fitted parameters.

for (int ixbin = 1, ixbin < h2->GetNbinsX(); ++ixbin) { 
    // set initial parameter in the function
    f->SetParameters(........)
    h2->FitSliceY(f,ixbin,ixbin)
    // merge here histogram with fitted parameters
    .....
}

Best Regards

Lorenzo