doc/v630/rf103__interprfuncs_8C.html

#include "RooRealVar.h"

#include "RooDataSet.h"

#include "RooGaussian.h"

#include "TCanvas.h"

#include "TAxis.h"

#include "RooPlot.h"

#include "RooFitResult.h"

#include "RooGenericPdf.h"


using namespace RooFit;


void rf103_interprfuncs()

{

   // ----------------------------------------------------

   // G e n e r i c   i n t e r p r e t e d   p . d . f .

   // ====================================================


   // Declare observable x

   RooRealVar x("x", "x", -20, 20);


   // C o n s t r u c t   g e n e r i c   p d f   f r o m   i n t e r p r e t e d   e x p r e s s i o n

   // -------------------------------------------------------------------------------------------------


   // To construct a proper pdf, the formula expression is explicitly normalized internally by dividing

   // it by a numeric integral of the expression over x in the range [-20,20]

   //

   RooRealVar alpha("alpha", "alpha", 5, 0.1, 10);

   RooGenericPdf genpdf("genpdf", "genpdf", "(1+0.1*abs(x)+sin(sqrt(abs(x*alpha+0.1))))", RooArgSet(x, alpha));


   // S a m p l e ,   f i t   a n d   p l o t   g e n e r i c   p d f

   // ---------------------------------------------------------------


   // Generate a toy dataset from the interpreted pdf

   std::unique_ptr<RooDataSet> data{genpdf.generate(x, 10000)};


   // Fit the interpreted pdf to the generated data

   genpdf.fitTo(*data, PrintLevel(-1));


   // Make a plot of the data and the pdf overlaid

   RooPlot *xframe = x.frame(Title("Interpreted expression pdf"));

   data->plotOn(xframe);

   genpdf.plotOn(xframe);


   // -----------------------------------------------------------------------------------------------------------

   // S t a n d a r d   p . d . f   a d j u s t   w i t h   i n t e r p r e t e d   h e l p e r   f u n c t i o n

   // ==========================================================================================================

   // Make a gauss(x,sqrt(mean2),sigma) from a standard RooGaussian


   // C o n s t r u c t   s t a n d a r d   p d f  w i t h   f o r m u l a   r e p l a c i n g   p a r a m e t e r

   // ------------------------------------------------------------------------------------------------------------


   // Construct parameter mean2 and sigma

   RooRealVar mean2("mean2", "mean^2", 10, 0, 200);

   RooRealVar sigma("sigma", "sigma", 3, 0.1, 10);


   // Construct interpreted function mean = sqrt(mean^2)

   RooFormulaVar mean("mean", "mean", "sqrt(mean2)", mean2);


   // Construct a gaussian g2(x,sqrt(mean2),sigma) ;

   RooGaussian g2("g2", "h2", x, mean, sigma);


   // G e n e r a t e   t o y   d a t a

   // ---------------------------------


   // Construct a separate gaussian g1(x,10,3) to generate a toy Gaussian dataset with mean 10 and width 3

   RooGaussian g1("g1", "g1", x, 10.0, 3.0);

   std::unique_ptr<RooDataSet> data2{g1.generate(x, 1000)};


   // F i t   a n d   p l o t   t a i l o r e d   s t a n d a r d   p d f

   // -------------------------------------------------------------------


   // Fit g2 to data from g1

   std::unique_ptr<RooFitResult> fitResult{g2.fitTo(*data2, Save(), PrintLevel(-1))};

   fitResult->Print();


   // Plot data on frame and overlay projection of g2

   RooPlot *xframe2 = x.frame(Title("Tailored Gaussian pdf"));

   data2->plotOn(xframe2);

   g2.plotOn(xframe2);


   // Draw all frames on a canvas

   TCanvas *c = new TCanvas("rf103_interprfuncs", "rf103_interprfuncs", 800, 400);

   c->Divide(2);

   c->cd(1);

   gPad->SetLeftMargin(0.15);

   xframe->GetYaxis()->SetTitleOffset(1.4);

   xframe->Draw();

   c->cd(2);

   gPad->SetLeftMargin(0.15);

   xframe2->GetYaxis()->SetTitleOffset(1.4);

   xframe2->Draw();

}

c
#define c(i)
Definition RSha256.hxx:101

RooDataSet.h

RooFitResult.h

RooGaussian.h

RooGenericPdf.h

RooPlot.h

RooRealVar.h

TAxis.h

TCanvas.h

data
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void data
Definition TGWin32VirtualXProxy.cxx:104

gPad
#define gPad
Definition TVirtualPad.h:305

RooArgSet
RooArgSet is a container object that can hold multiple RooAbsArg objects.
Definition RooArgSet.h:55

RooFormulaVar
A RooFormulaVar is a generic implementation of a real-valued object, which takes a RooArgList of serv...
Definition RooFormulaVar.h:30

RooGaussian
Plain Gaussian p.d.f.
Definition RooGaussian.h:24

RooGenericPdf
RooGenericPdf is a concrete implementation of a probability density function, which takes a RooArgLis...
Definition RooGenericPdf.h:25

RooPlot
A RooPlot is a plot frame and a container for graphics objects within that frame.
Definition RooPlot.h:43

RooPlot::frame
static RooPlot * frame(const RooAbsRealLValue &var, double xmin, double xmax, Int_t nBins)
Create a new frame for a given variable in x.
Definition RooPlot.cxx:239

RooPlot::GetYaxis
TAxis * GetYaxis() const
Definition RooPlot.cxx:1279

RooPlot::Draw
void Draw(Option_t *options=nullptr) override
Draw this plot and all of the elements it contains.
Definition RooPlot.cxx:652

RooRealVar
RooRealVar represents a variable that can be changed from the outside.
Definition RooRealVar.h:37

TAttAxis::SetTitleOffset
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title.
Definition TAttAxis.cxx:298

TCanvas
The Canvas class.
Definition TCanvas.h:23

RooFit::Save
RooCmdArg Save(bool flag=true)
Definition RooGlobalFunc.cxx:564

RooFit::PrintLevel
RooCmdArg PrintLevel(Int_t code)
Definition RooGlobalFunc.cxx:572

sigma
const Double_t sigma
Definition h1analysisProxy.h:11

x
Double_t x[n]
Definition legend1.C:17

RooFit
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...
Definition JSONIO.h:26

rf103_interprfuncs
Definition rf103_interprfuncs.py:1

xmlio::Title
const char * Title
Definition TXMLSetup.cxx:68