rf204_extrangefit.C: 'ADDITION AND CONVOLUTION' RooFit tutorial macro #204
//////////////////////////////////////////////////////////////////////////
//
// 'ADDITION AND CONVOLUTION' RooFit tutorial macro #204
//
// Extended maximum likelihood fit with alternate range definition
// for observed number of events.
//
//
//
// 07/2008 - Wouter Verkerke
//
/////////////////////////////////////////////////////////////////////////
#ifndef __CINT__
#include "RooGlobalFunc.h"
#endif
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooChebychev.h"
#include "RooAddPdf.h"
#include "RooExtendPdf.h"
#include "RooFitResult.h"
#include "TCanvas.h"
#include "RooPlot.h"
using namespace RooFit ;
void rf204_extrangefit()
{
// S e t u p c o m p o n e n t p d f s
// ---------------------------------------
// Declare observable x
RooRealVar x("x","x",0,10) ;
// Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and their paramaters
RooRealVar mean("mean","mean of gaussians",5) ;
RooRealVar sigma1("sigma1","width of gaussians",0.5) ;
RooRealVar sigma2("sigma2","width of gaussians",1) ;
RooGaussian sig1("sig1","Signal component 1",x,mean,sigma1) ;
RooGaussian sig2("sig2","Signal component 2",x,mean,sigma2) ;
// Build Chebychev polynomial p.d.f.
RooRealVar a0("a0","a0",0.5,0.,1.) ;
RooRealVar a1("a1","a1",-0.2,0.,1.) ;
RooChebychev bkg("bkg","Background",x,RooArgSet(a0,a1)) ;
// Sum the signal components into a composite signal p.d.f.
RooRealVar sig1frac("sig1frac","fraction of component 1 in signal",0.8,0.,1.) ;
RooAddPdf sig("sig","Signal",RooArgList(sig1,sig2),sig1frac) ;
// C o n s t r u c t e x t e n d e d c o m p s wi t h r a n g e s p e c
// ------------------------------------------------------------------------------
// Define signal range in which events counts are to be defined
x.setRange("signalRange",4,6) ;
// Associated nsig/nbkg as expected number of events with sig/bkg _in_the_range_ "signalRange"
RooRealVar nsig("nsig","number of signal events in signalRange",500,0.,10000) ;
RooRealVar nbkg("nbkg","number of background events in signalRange",500,0,10000) ;
RooExtendPdf esig("esig","extended signal p.d.f",sig,nsig,"signalRange") ;
RooExtendPdf ebkg("ebkg","extended background p.d.f",bkg,nbkg,"signalRange") ;
// S u m e x t e n d e d c o m p o n e n t s
// ---------------------------------------------
// Construct sum of two extended p.d.f. (no coefficients required)
RooAddPdf model("model","(g1+g2)+a",RooArgList(ebkg,esig)) ;
// S a m p l e d a t a , f i t m o d e l
// -------------------------------------------
// Generate 1000 events from model so that nsig,nbkg come out to numbers <<500 in fit
RooDataSet *data = model.generate(x,1000) ;
// Perform unbinned extended ML fit to data
RooFitResult* r = model.fitTo(*data,Extended(kTRUE),Save()) ;
r->Print() ;
}
Last change: Wed Dec 17 10:56:33 2008
Last generated: 2008-12-17 10:56
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