How to access RooFitResult for chi2FitTo() method?

[pkalbhor]

I would like to save RooFitResult Object returned by chi2FitTo method which is implemented in rf609__xychi2fit_8C
There is this line in the code which does chi2 fit to unbinned dataset.

f.chi2FitTo(dxy, YVar(y), Integrate(kTRUE));

What I would like to do is save returned object from this method. Which I do as below:

RooFitResult *res= f.chi2FitTo(dxy, YVar(y), Integrate(kTRUE));
res->Print();

It gives error as

rf609_xychi2fit.C:75:5: warning: null passed to a callee that requires a non-null argument [-Wnonnull]

I was expecting that this object res should contain input and output parameters of the fit. But it is saving null pointer. Why is that?

[StephanH]

See the argument Save in the documentation of the function here:
https://root.cern.ch/doc/master/classRooAbsPdf.html#ab4fd4f71f1cee1f8bce9811801f7c40f

[pkalbhor]

Thanks Stephan,
Needed to provide Save(1) argument. Like:

RooFitResult *res= f.chi2FitTo(dxy, YVar(y), Integrate(kTRUE), Save(1));