Logo ROOT   6.16/01
Reference Guide
rf704_amplitudefit.C
Go to the documentation of this file.
1/// \file
2/// \ingroup tutorial_roofit
3/// \notebook
4/// 'SPECIAL PDFS' RooFit tutorial macro #704
5///
6/// Using a p.d.f defined by a sum of real-valued amplitude components
7///
8/// \macro_image
9/// \macro_output
10/// \macro_code
11/// \author 07/2008 - Wouter Verkerke
12
13
14#include "RooRealVar.h"
15#include "RooDataSet.h"
16#include "RooGaussian.h"
17#include "RooConstVar.h"
18#include "RooTruthModel.h"
19#include "RooFormulaVar.h"
20#include "RooRealSumPdf.h"
21#include "RooPolyVar.h"
22#include "RooProduct.h"
23#include "TH1.h"
24#include "TCanvas.h"
25#include "TAxis.h"
26#include "RooPlot.h"
27using namespace RooFit ;
28
29
31{
32 // S e t u p 2 D a m p l i t u d e f u n c t i o n s
33 // -------------------------------------------------------
34
35 // Observables
36 RooRealVar t("t","time",-1.,15.);
37 RooRealVar cosa("cosa","cos(alpha)",-1.,1.);
38
39 // Use RooTruthModel to obtain compiled implementation of sinh/cosh modulated decay functions
40 RooRealVar tau("tau","#tau",1.5);
41 RooRealVar deltaGamma("deltaGamma","deltaGamma", 0.3);
42 RooTruthModel truthModel("tm","tm",t) ;
43 RooFormulaVar coshGBasis("coshGBasis","exp(-@0/ @1)*cosh(@0*@2/2)",RooArgList(t,tau,deltaGamma));
44 RooFormulaVar sinhGBasis("sinhGBasis","exp(-@0/ @1)*sinh(@0*@2/2)",RooArgList(t,tau,deltaGamma));
45 RooAbsReal* coshGConv = truthModel.convolution(&coshGBasis,&t);
46 RooAbsReal* sinhGConv = truthModel.convolution(&sinhGBasis,&t);
47
48 // Construct polynomial amplitudes in cos(a)
49 RooPolyVar poly1("poly1","poly1",cosa,RooArgList(RooConst(0.5),RooConst(0.2),RooConst(0.2)),0);
50 RooPolyVar poly2("poly2","poly2",cosa,RooArgList(RooConst(1),RooConst(-0.2),RooConst(3)),0);
51
52 // Construct 2D amplitude as uncorrelated product of amp(t)*amp(cosa)
53 RooProduct ampl1("ampl1","amplitude 1",RooArgSet(poly1,*coshGConv));
54 RooProduct ampl2("ampl2","amplitude 2",RooArgSet(poly2,*sinhGConv));
55
56
57
58 // C o n s t r u c t a m p l i t u d e s u m p d f
59 // -----------------------------------------------------
60
61 // Amplitude strengths
62 RooRealVar f1("f1","f1",1,0,2) ;
63 RooRealVar f2("f2","f2",0.5,0,2) ;
64
65 // Construct pdf
66 RooRealSumPdf pdf("pdf","pdf",RooArgList(ampl1,ampl2),RooArgList(f1,f2)) ;
67
68 // Generate some toy data from pdf
69 RooDataSet* data = pdf.generate(RooArgSet(t,cosa),10000);
70
71 // Fit pdf to toy data with only amplitude strength floating
72 pdf.fitTo(*data) ;
73
74
75
76 // P l o t a m p l i t u d e s u m p d f
77 // -------------------------------------------
78
79 // Make 2D plots of amplitudes
80 TH1* hh_cos = ampl1.createHistogram("hh_cos",t,Binning(50),YVar(cosa,Binning(50))) ;
81 TH1* hh_sin = ampl2.createHistogram("hh_sin",t,Binning(50),YVar(cosa,Binning(50))) ;
82 hh_cos->SetLineColor(kBlue) ;
83 hh_sin->SetLineColor(kRed) ;
84
85
86 // Make projection on t, plot data, pdf and its components
87 // Note component projections may be larger than sum because amplitudes can be negative
88 RooPlot* frame1 = t.frame();
89 data->plotOn(frame1);
90 pdf.plotOn(frame1);
91 pdf.plotOn(frame1,Components(ampl1),LineStyle(kDashed));
92 pdf.plotOn(frame1,Components(ampl2),LineStyle(kDashed),LineColor(kRed));
93
94 // Make projection on cosa, plot data, pdf and its components
95 // Note that components projection may be larger than sum because amplitudes can be negative
96 RooPlot* frame2 = cosa.frame();
97 data->plotOn(frame2);
98 pdf.plotOn(frame2);
99 pdf.plotOn(frame2,Components(ampl1),LineStyle(kDashed));
100 pdf.plotOn(frame2,Components(ampl2),LineStyle(kDashed),LineColor(kRed));
101
102
103
104 TCanvas* c = new TCanvas("rf704_amplitudefit","rf704_amplitudefit",800,800) ;
105 c->Divide(2,2) ;
106 c->cd(1) ; gPad->SetLeftMargin(0.15) ; frame1->GetYaxis()->SetTitleOffset(1.4) ; frame1->Draw();
107 c->cd(2) ; gPad->SetLeftMargin(0.15) ; frame2->GetYaxis()->SetTitleOffset(1.4) ; frame2->Draw();
108 c->cd(3) ; gPad->SetLeftMargin(0.20) ; hh_cos->GetZaxis()->SetTitleOffset(2.3) ; hh_cos->Draw("surf") ;
109 c->cd(4) ; gPad->SetLeftMargin(0.20) ; hh_sin->GetZaxis()->SetTitleOffset(2.3) ; hh_sin->Draw("surf") ;
110
111
112}
#define c(i)
Definition: RSha256.hxx:101
@ kRed
Definition: Rtypes.h:63
@ kBlue
Definition: Rtypes.h:63
@ kDashed
Definition: TAttLine.h:48
#define gPad
Definition: TVirtualPad.h:286
RooAbsReal is the common abstract base class for objects that represent a real value and implements f...
Definition: RooAbsReal.h:53
RooArgSet is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgSet.h:28
RooDataSet is a container class to hold unbinned data.
Definition: RooDataSet.h:31
A RooPlot is a plot frame and a container for graphics objects within that frame.
Definition: RooPlot.h:41
TAxis * GetYaxis() const
Definition: RooPlot.cxx:1123
virtual void Draw(Option_t *options=0)
Draw this plot and all of the elements it contains.
Definition: RooPlot.cxx:558
Class RooPolyVar is a RooAbsReal implementing a polynomial in terms of a list of RooAbsReal coefficie...
Definition: RooPolyVar.h:28
RooProduct a RooAbsReal implementation that represent the product of a given set of other RooAbsReal ...
Definition: RooProduct.h:32
Class RooRealSumPdf implements a PDF constructed from a sum of functions:
Definition: RooRealSumPdf.h:24
RooRealVar represents a fundamental (non-derived) real valued object.
Definition: RooRealVar.h:36
RooTruthModel is an implementation of RooResolution model that provides a delta-function resolution m...
Definition: RooTruthModel.h:21
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title Offset is a correction factor with respect to the "s...
Definition: TAttAxis.cxx:294
virtual void SetLineColor(Color_t lcolor)
Set the line color.
Definition: TAttLine.h:40
The Canvas class.
Definition: TCanvas.h:31
The TH1 histogram class.
Definition: TH1.h:56
TAxis * GetZaxis()
Definition: TH1.h:318
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition: TH1.cxx:2974
TF1 * f1
Definition: legend1.C:11
RooCmdArg Binning(const RooAbsBinning &binning)
RooCmdArg YVar(const RooAbsRealLValue &var, const RooCmdArg &arg=RooCmdArg::none())
RooCmdArg Components(const RooArgSet &compSet)
RooConstVar & RooConst(Double_t val)
RooCmdArg LineColor(Color_t color)
RooCmdArg LineStyle(Style_t style)