rf312_multirangefit.C File Reference

Detailed Description

'MULTIDIMENSIONAL MODELS' RooFit tutorial macro #312

Performing fits in multiple (disjoint) ranges in one or more dimensions

Processing /mnt/build/workspace/root-makedoc-v608/rootspi/rdoc/src/v6-08-00-patches/tutorials/roofit/rf312_multirangefit.C...

#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooConstVar.h"
#include "RooProdPdf.h"
#include "RooAddPdf.h"
#include "RooPolynomial.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
#include "RooFitResult.h"
using namespace RooFit ;


void rf312_multirangefit()
{

   // C r e a t e   2 D   p d f   a n d   d a t a 
   // -------------------------------------------

   // Define observables x,y
   RooRealVar x("x","x",-10,10) ;
   RooRealVar y("y","y",-10,10) ;

   // Construct the signal pdf gauss(x)*gauss(y)
   RooRealVar mx("mx","mx",1,-10,10) ;
   RooRealVar my("my","my",1,-10,10) ;

   RooGaussian gx("gx","gx",x,mx,RooConst(1)) ;
   RooGaussian gy("gy","gy",y,my,RooConst(1)) ;

   RooProdPdf sig("sig","sig",gx,gy) ;

   // Construct the background pdf (flat in x,y)
   RooPolynomial px("px","px",x) ;
   RooPolynomial py("py","py",y) ;
   RooProdPdf bkg("bkg","bkg",px,py) ;

   // Construct the composite model sig+bkg
   RooRealVar f("f","f",0.,1.) ;
   RooAddPdf model("model","model",RooArgList(sig,bkg),f) ;

   // Sample 10000 events in (x,y) from the model
   RooDataSet* modelData = model.generate(RooArgSet(x,y),10000) ;



   // D e f i n e   s i g n a l   a n d   s i d e b a n d   r e g i o n s
   // -------------------------------------------------------------------

   // Construct the SideBand1,SideBand2,Signal regions
   //
   //                    |
   //      +-------------+-----------+                 
   //      |             |           |             
   //      |    Side     |   Sig     |        
   //      |    Band1    |   nal     |             
   //      |             |           |            
   //    --+-------------+-----------+--   
   //      |                         |       
   //      |           Side          |        
   //      |           Band2         |            
   //      |                         |          
   //      +-------------+-----------+            
   //                    |                       

   x.setRange("SB1",-10,+10) ;
   y.setRange("SB1",-10,0) ;

   x.setRange("SB2",-10,0) ;
   y.setRange("SB2",0,+10) ;

   x.setRange("SIG",0,+10) ;
   y.setRange("SIG",0,+10) ;

   x.setRange("FULL",-10,+10) ;
   y.setRange("FULL",-10,+10) ;


   // P e r f o r m   f i t s   i n   i n d i v i d u a l   s i d e b a n d   r e g i o n s
   // -------------------------------------------------------------------------------------

   // Perform fit in SideBand1 region (RooAddPdf coefficients will be interpreted in full range)
   RooFitResult* r_sb1 = model.fitTo(*modelData,Range("SB1"),Save()) ;

   // Perform fit in SideBand2 region (RooAddPdf coefficients will be interpreted in full range)
   RooFitResult* r_sb2 = model.fitTo(*modelData,Range("SB2"),Save()) ;



   // P e r f o r m   f i t s   i n   j o i n t    s i d e b a n d   r e g i o n s
   // -----------------------------------------------------------------------------

   // Now perform fit to joint 'L-shaped' sideband region 'SB1|SB2' 
   // (RooAddPdf coefficients will be interpreted in full range)
   RooFitResult* r_sb12 = model.fitTo(*modelData,Range("SB1,SB2"),Save()) ;


   // Print results for comparison
   r_sb1->Print() ;
   r_sb2->Print() ;
   r_sb12->Print() ;


}

Author

07/2008 - Wouter Verkerke

Definition in file rf312_multirangefit.C.