ROOT   Reference Guide
rf110_normintegration.C
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1/// \file
2/// \ingroup tutorial_roofit
3/// \notebook -js
4/// Basic functionality: normalization and integration of pdfs, construction of cumulative distribution
5/// monodimensional functions
6///
7/// \macro_image
8/// \macro_output
9/// \macro_code
10///
11/// \date July 2008
12/// \author Wouter Verkerke
13
14#include "RooRealVar.h"
15#include "RooGaussian.h"
16#include "RooConstVar.h"
17#include "RooAbsReal.h"
18#include "RooPlot.h"
19#include "TCanvas.h"
20#include "TAxis.h"
21using namespace RooFit;
22
24{
25 // S e t u p m o d e l
26 // ---------------------
27
28 // Create observables x,y
29 RooRealVar x("x", "x", -10, 10);
30
31 // Create pdf gaussx(x,-2,3)
32 RooGaussian gx("gx", "gx", x, RooConst(-2), RooConst(3));
33
34 // R e t r i e v e r a w & n o r m a l i z e d v a l u e s o f R o o F i t p . d . f . s
35 // --------------------------------------------------------------------------------------------------
36
37 // Return 'raw' unnormalized value of gx
38 cout << "gx = " << gx.getVal() << endl;
39
40 // Return value of gx normalized over x in range [-10,10]
41 RooArgSet nset(x);
42 cout << "gx_Norm[x] = " << gx.getVal(&nset) << endl;
43
44 // Create object representing integral over gx
45 // which is used to calculate gx_Norm[x] == gx / gx_Int[x]
46 RooAbsReal *igx = gx.createIntegral(x);
47 cout << "gx_Int[x] = " << igx->getVal() << endl;
48
49 // I n t e g r a t e n o r m a l i z e d p d f o v e r s u b r a n g e
50 // ----------------------------------------------------------------------------
51
52 // Define a range named "signal" in x from -5,5
53 x.setRange("signal", -5, 5);
54
55 // Create an integral of gx_Norm[x] over x in range "signal"
56 // This is the fraction of of pdf gx_Norm[x] which is in the
57 // range named "signal"
58 RooAbsReal *igx_sig = gx.createIntegral(x, NormSet(x), Range("signal"));
59 cout << "gx_Int[x|signal]_Norm[x] = " << igx_sig->getVal() << endl;
60
61 // C o n s t r u c t c u m u l a t i v e d i s t r i b u t i o n f u n c t i o n f r o m p d f
62 // -----------------------------------------------------------------------------------------------------
63
64 // Create the cumulative distribution function of gx
65 // i.e. calculate Int[-10,x] gx(x') dx'
66 RooAbsReal *gx_cdf = gx.createCdf(x);
67
68 // Plot cdf of gx versus x
69 RooPlot *frame = x.frame(Title("cdf of Gaussian pdf"));
70 gx_cdf->plotOn(frame);
71
72 // Draw plot on canvas
73 new TCanvas("rf110_normintegration", "rf110_normintegration", 600, 600);
75 frame->GetYaxis()->SetTitleOffset(1.6);
76 frame->Draw();
77}
RooAbsReal is the common abstract base class for objects that represent a real value and implements f...
Definition: RooAbsReal.h:62
double getVal(const RooArgSet *normalisationSet=nullptr) const
Evaluate object.
Definition: RooAbsReal.h:91
RooAbsReal * createIntegral(const RooArgSet &iset, const RooCmdArg &arg1, const RooCmdArg &arg2=RooCmdArg::none(), const RooCmdArg &arg3=RooCmdArg::none(), const RooCmdArg &arg4=RooCmdArg::none(), const RooCmdArg &arg5=RooCmdArg::none(), const RooCmdArg &arg6=RooCmdArg::none(), const RooCmdArg &arg7=RooCmdArg::none(), const RooCmdArg &arg8=RooCmdArg::none()) const
Create an object that represents the integral of the function over one or more observables std::liste...
Definition: RooAbsReal.cxx:522
virtual RooPlot * plotOn(RooPlot *frame, const RooCmdArg &arg1=RooCmdArg(), const RooCmdArg &arg2=RooCmdArg(), const RooCmdArg &arg3=RooCmdArg(), const RooCmdArg &arg4=RooCmdArg(), const RooCmdArg &arg5=RooCmdArg(), const RooCmdArg &arg6=RooCmdArg(), const RooCmdArg &arg7=RooCmdArg(), const RooCmdArg &arg8=RooCmdArg(), const RooCmdArg &arg9=RooCmdArg(), const RooCmdArg &arg10=RooCmdArg()) const
Plot (project) PDF on specified frame.
RooArgSet is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgSet.h:56
Plain Gaussian p.d.f.
Definition: RooGaussian.h:24
A RooPlot is a plot frame and a container for graphics objects within that frame.
Definition: RooPlot.h:43
TAxis * GetYaxis() const
Definition: RooPlot.cxx:1276
void Draw(Option_t *options=nullptr) override
Draw this plot and all of the elements it contains.
Definition: RooPlot.cxx:649
RooRealVar represents a variable that can be changed from the outside.
Definition: RooRealVar.h:40
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title.
Definition: TAttAxis.cxx:301
The Canvas class.
Definition: TCanvas.h:23
RooConstVar & RooConst(double val)
RooCmdArg NormSet(Args_t &&... argsOrArgSet)
Double_t x[n]
Definition: legend1.C:17
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...
Definition: Common.h:18
const char * Title
Definition: TXMLSetup.cxx:68
Ta Range(0, 0, 1, 1)