doc/v632/rf101__basics_8C.html

#include "RooRealVar.h"

#include "RooDataSet.h"

#include "RooGaussian.h"

#include "TCanvas.h"

#include "RooPlot.h"

#include "TAxis.h"

using namespace RooFit;


void rf101_basics()

{

   // S e t u p   m o d e l

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


   // Declare variables x,mean,sigma with associated name, title, initial value and allowed range

   RooRealVar x("x", "x", -10, 10);

   RooRealVar mean("mean", "mean of gaussian", 1, -10, 10);

   RooRealVar sigma("sigma", "width of gaussian", 1, 0.1, 10);


   // Build gaussian pdf in terms of x,mean and sigma

   RooGaussian gauss("gauss", "gaussian PDF", x, mean, sigma);


   // Construct plot frame in 'x'

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


   // P l o t   m o d e l   a n d   c h a n g e   p a r a m e t e r   v a l u e s

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


   // Plot gauss in frame (i.e. in x)

   gauss.plotOn(xframe);


   // Change the value of sigma to 3

   sigma.setVal(3);


   // Plot gauss in frame (i.e. in x) and draw frame on canvas

   gauss.plotOn(xframe, LineColor(kRed));


   // G e n e r a t e   e v e n t s

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


   // Generate a dataset of 1000 events in x from gauss

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


   // Make a second plot frame in x and draw both the

   // data and the pdf in the frame

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

   data->plotOn(xframe2);

   gauss.plotOn(xframe2);


   // F i t   m o d e l   t o   d a t a

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


   // Fit pdf to data

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


   // Print values of mean and sigma (that now reflect fitted values and errors)

   mean.Print();

   sigma.Print();


   // Draw all frames on a canvas

   TCanvas *c = new TCanvas("rf101_basics", "rf101_basics", 800, 400); c->Divide(2);

   c->cd(1);

   gPad->SetLeftMargin(0.15);

   xframe->GetYaxis()->SetTitleOffset(1.6);

   xframe->Draw();

   c->cd(2);

   gPad->SetLeftMargin(0.15);

   xframe2->GetYaxis()->SetTitleOffset(1.6);

   xframe2->Draw();

}

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

RooDataSet.h

RooGaussian.h

RooPlot.h

RooRealVar.h

kRed
@ kRed
Definition Rtypes.h:66

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

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

RooPlot
Plot frame and a container for graphics objects within that frame.
Definition RooPlot.h:45

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:225

RooPlot::GetYaxis
TAxis * GetYaxis() const
Definition RooPlot.cxx:1264

RooPlot::Draw
void Draw(Option_t *options=nullptr) override
Draw this plot and all of the elements it contains.
Definition RooPlot.cxx:637

RooRealVar
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

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

rf101_basics
Definition rf101_basics.py:1