using namespace RooFit;

void ForumPost(){
  TFile *f = new TFile("$HOME/Downloads/Linefit.root");
  TTree *t = (TTree*)f->Get("G2 m4 T");
  
  RooRealVar En("Energy","Energy",300,1000);

  RooRealVar mean("mean","mean",735);
  RooRealVar fwhm("fwhm","fwhm",5);
  RooGaussian gss("gss","gss",En,mean,fwhm);
  
  RooRealVar mean630("mean630","mean",630, 610, 660);
  RooRealVar fwhm630("fwhm630","fwhm", 30, 1, 50);
  RooBreitWigner gss630("gss630","gss",En, mean630, fwhm630);

  RooRealVar mean700("mean700","mean",700, 695, 710);
  RooRealVar fwhm700("fwhm700","fwhm", 2, 0.01, 50);
  RooBreitWigner gss700("gss700","gss",En, mean700, fwhm700);
  

  
  RooRealVar mean800("mean800","mean",800, 790, 820);
  RooRealVar fwhm800("fwhm800","fwhm",10, 1, 50);
  RooGaussian gss800("gss800","gss", En, mean800, fwhm800);

  RooRealVar c1("c1","c1",1,-1000,1000);
  RooRealVar c2("c2","c2",1,1.E-5,1000);
  RooGenericPdf linear("linear","c1+c2*(Energy)",RooArgList(c1,c2,En));
  
  RooRealVar coef1("coef1","c1",1,-30,30);
  RooRealVar coef2("coef2","c2",1,-30,30);
  RooRealVar coef3("coef3","c2",1,-30,30);
  
  RooPolynomial pol("pol", "pol", En, RooArgList(coef1, coef2, coef3));

  RooRealVar sigy("sigy","sigy",1,0,10000);
  RooRealVar sig630("sig630","sigy",500,0,10000);
  RooRealVar sig700("sig700","sigy",100,20,200);
  RooRealVar sig800("sig800","sigy",1,0,10000);
  RooRealVar bkgy("bkgy","bkgy",1,0,10000);

  RooAddPdf model("model","model",RooArgList(gss, gss630, gss700, gss800, pol),
    RooArgList(sigy, sig630, sig700, sig800, bkgy));

  RooDataSet data("data","data",RooArgSet(En),Import(*t));

  model.fitTo(data,Range(400, 1000),Extended());

  RooPlot *P = En.frame();
  data.plotOn(P);
  model.plotOn(P);
  model.plotOn(P,Components(gss),LineColor(kRed));
  model.paramOn(P);
  P->Draw();
}