Explain RooAbsPdf?

Can someone explain what the ROOFIT class RooAbsPdf does? Does it hold a function which needs to be defined?

@belle, maybe documentation could be helpful for you? https://root.cern.ch/doc/v614/classRooAbsPdf.html

It only refers to it as a pdf: in ROOT, does that mean that it needs to contain/reference to another function?

I am not really roofit expert, but maybe check these two tutorials. Fists we generate our workspace https://root.cern.ch/doc/master/rf502__wspacewrite_8C.html

 RooAddPdf model("model","g1+g2+a",RooArgList(bkg,sig),bkgfrac) ;

while in https://root.cern.ch/doc/master/rf503__wspaceread_8C.html we can retrieve model via

RooWorkspace* w = (RooWorkspace*) f->Get("w");
 RooAbsPdf* model = w->pdf("model");

So the RooAbsPdf does need to have a function inputted? There’s no way to make it choose what function to use?

RooAbsPdf is a base class describing any PDF in RooFit. You can create your PDF with the function as you like using pre-defined PDF classes such as RooGaussian, RooExponential, etc… and by combining them using various helper classes (e.g. RooAddPdf).
You can also input your own functions and create PDF classes that derive from RooAbsPdf.
The best is if you see the RooFit Quick Start Guide (http://root.cern.ch/download/doc/roofit_quickstart_3.00.pdf

Lorenzo

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