using namespace RooFit;

void PlotSumPDF()
{
// Build two Gaussian PDFs 
RooRealVar x("x","x",0,10) ; 
RooRealVar mean1("mean1","mean of gaussian 1",2) ; 
RooRealVar mean2("mean2","mean of gaussian 2",3) ; 
RooRealVar sigma1("sigma1","width of gaussian 1",1) ; 
RooRealVar sigma2("sigma2","width of gaussian 2",1.5) ; 
RooGaussian gauss1("gauss1","gaussian PDF",x,mean1,sigma1) ;  
RooGaussian gauss2("gauss2","gaussian PDF",x,mean2,sigma2) ;  
  
// Build Argus background PDF 
RooRealVar argpar("argpar","argus shape parameter",-1.0) ; 
RooRealVar cutoff("cutoff","argus cutoff",10.0) ; 
RooArgusBG argus("argus","Argus PDF",x,cutoff,argpar) ; 
// Add the components 
RooRealVar g1frac("g1frac","fraction of gauss1",0.5) ; 
RooRealVar g2frac("g2frac","fraction of gauss2",0.1) ; 
RooAddPdf  sum("sum","g1+g2+a",RooArgList(gauss1,gauss2,argus), 
                               RooArgList(g1frac,g2frac)) ; 


							   
// Generate a toyMC sample 
RooDataSet *data = 
     sum.generate(x,10000) ; 
  
// Plot data and PDF overlaid 
 RooPlot* xframe = x.frame(Title("MC data and PDFs overlaid")) ; 
data->plotOn(xframe) ; 
sum->plotOn(xframe) ;
sum->plotOn(xframe, Components(argus), LineStyle(kDashed)); 
sum->plotOn(xframe,LineColor(kRed), Components(RooArgSet(gauss2))) ; 
// Plot only argus and gauss2 
//sum->plotOn(xframe, Components(RooArgSet(argus, gauss2)), LineStyle(kDashed)); 
xframe->Draw() ; 

}