rf313_paramranges.C

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/// \file
/// \ingroup tutorial_roofit
/// \notebook -js
///  'MULTIDIMENSIONAL MODELS' RooFit tutorial macro #313
///
///  Working with parametrized ranges to define non-rectangular regions
///  for fitting and integration
///
/// \macro_image
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke


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


void rf313_paramranges()
{

   // C r e a t e   3 D   p d f
   // -------------------------

   // Define observable (x,y,z)
   RooRealVar x("x","x",0,10) ;
   RooRealVar y("y","y",0,10) ;
   RooRealVar z("z","z",0,10) ;

   // Define 3 dimensional pdf
   RooRealVar z0("z0","z0",-0.1,1) ;
   RooPolynomial px("px","px",x,RooConst(0)) ;
   RooPolynomial py("py","py",y,RooConst(0)) ;
   RooPolynomial pz("pz","pz",z,z0) ;
   RooProdPdf pxyz("pxyz","pxyz",RooArgSet(px,py,pz)) ;



   // D e f i n e d   n o n - r e c t a n g u l a r   r e g i o n   R   i n   ( x , y , z )
   // -------------------------------------------------------------------------------------

   //
   // R = Z[0 - 0.1*Y^2] * Y[0.1*X - 0.9*X] * X[0 - 10]
   //

   // Construct range parametrized in "R" in y [ 0.1*x, 0.9*x ]
   RooFormulaVar ylo("ylo","0.1*x",x) ;
   RooFormulaVar yhi("yhi","0.9*x",x) ;
   y.setRange("R",ylo,yhi) ;

   // Construct parametrized ranged "R" in z [ 0, 0.1*y^2 ]
   RooFormulaVar zlo("zlo","0.0*y",y) ;
   RooFormulaVar zhi("zhi","0.1*y*y",y) ;
   z.setRange("R",zlo,zhi) ;



   // C a l c u l a t e   i n t e g r a l   o f   n o r m a l i z e d   p d f   i n   R
   // ----------------------------------------------------------------------------------

   // Create integral over normalized pdf model over x,y,z in "R" region
   RooAbsReal* intPdf = pxyz.createIntegral(RooArgSet(x,y,z),RooArgSet(x,y,z),"R") ;

   // Plot value of integral as function of pdf parameter z0
   RooPlot* frame = z0.frame(Title("Integral of pxyz over x,y,z in region R")) ;
   intPdf->plotOn(frame) ;



   new TCanvas("rf313_paramranges","rf313_paramranges",600,600) ;
   gPad->SetLeftMargin(0.15) ; frame->GetYaxis()->SetTitleOffset(1.6) ; frame->Draw() ;

   return ;
}