doc/hackathon/rf606__nllerrorhandling_8C.html

#include "RooRealVar.h"

#include "RooDataSet.h"

#include "RooArgusBG.h"

#include "TCanvas.h"

#include "TAxis.h"

#include "RooPlot.h"

using namespace RooFit;


void rf606_nllerrorhandling()

{

   // C r e a t e   m o d e l  a n d   d a t a s e t

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


   // Observable

   RooRealVar m("m", "m", 5.20, 5.30);


   // Parameters

   RooRealVar m0("m0", "m0", 5.291, 5.20, 5.30);

   RooRealVar k("k", "k", -30, -50, -10);


   // Pdf

   RooArgusBG argus("argus", "argus", m, m0, k);


   // Sample 1000 events in m from argus

   std::unique_ptr<RooDataSet> data{argus.generate(m, 1000)};


   // P l o t   m o d e l   a n d   d a t a

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


   RooPlot *frame1 = m.frame(Bins(40), Title("Argus model and data"));

   data->plotOn(frame1);

   argus.plotOn(frame1);


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

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


   // The ARGUS background shape has a sharp kinematic cutoff at m=m0

   // and is prone to evaluation errors if the cutoff parameter m0

   // is floated: when the pdf cutoff value is lower than that in data

   // events with m>m0 will have zero probability


   // Perform unbinned ML fit. Print detailed error messages for up to

   // 10 events per likelihood evaluation. The default error handling strategy

   // is to return a very high value of the likelihood to MINUIT if errors occur,

   // which will force MINUIT to retreat from the problematic area


   argus.fitTo(*data, PrintEvalErrors(10));


   // Perform another fit. In this configuration only the number of errors per

   // likelihood evaluation is shown, if it is greater than zero. The

   // EvalErrorWall(false) arguments disables the default error handling strategy

   // and will cause the actual (problematic) value of the likelihood to be passed

   // to MINUIT.

   //

   // NB: Use of this option is NOT recommended as default strategy as broken -log(L) values

   // can often be lower than 'good' ones because offending events are removed.

   // This may effectively create a false minimum in problem areas. This is clearly

   // illustrated in the second plot


   m0.setError(0.1);

   argus.fitTo(*data, PrintEvalErrors(0), EvalErrorWall(false));


   // P l o t   l i k e l i h o o d   a s   f u n c t i o n   o f   m 0

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


   // Construct likelihood function of model and data

   std::unique_ptr<RooAbsReal> nll{argus.createNLL(*data)};


   // Plot likelihood in m0 in range that includes problematic values

   // In this configuration no messages are printed for likelihood evaluation errors,

   // but if an likelihood value evaluates with error, the corresponding value

   // on the curve will be set to the value given in EvalErrorValue().


   RooPlot *frame2 = m0.frame(Range(5.288, 5.293), Title("-log(L) scan vs m0, problematic regions masked"));

   nll->plotOn(frame2, PrintEvalErrors(-1), ShiftToZero(), EvalErrorValue(nll->getVal() + 10), LineColor(kRed));

   frame2->SetMaximum(15);

   frame2->SetMinimum(0);


   TCanvas *c = new TCanvas("rf606_nllerrorhandling", "rf606_nllerrorhandling", 1200, 400);

   c->Divide(2);

   c->cd(1);

   gPad->SetLeftMargin(0.15);

   frame1->GetYaxis()->SetTitleOffset(1.4);

   frame1->Draw();

   c->cd(2);

   gPad->SetLeftMargin(0.15);

   frame2->GetYaxis()->SetTitleOffset(1.4);

   frame2->Draw();

}

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

RooArgusBG.h

RooDataSet.h

RooPlot.h

RooRealVar.h

kRed
@ kRed
Definition Rtypes.h:67

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:322

RooArgusBG
RooArgusBG is a RooAbsPdf implementation describing the ARGUS background shape.
Definition RooArgusBG.h:22

RooPlot
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:185

RooPlot::SetMinimum
virtual void SetMinimum(double minimum=-1111)
Set minimum value of Y axis.
Definition RooPlot.cxx:1013

RooPlot::SetMaximum
virtual void SetMaximum(double maximum=-1111)
Set maximum value of Y axis.
Definition RooPlot.cxx:1003

RooPlot::GetYaxis
TAxis * GetYaxis() const
Definition RooPlot.cxx:1230

RooPlot::Draw
void Draw(Option_t *options=nullptr) override
Draw this plot and all of the elements it contains.
Definition RooPlot.cxx:597

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:279

TCanvas
The Canvas class.
Definition TCanvas.h:23

RooFit::Title
RooCmdArg Title(const char *name)
Definition RooGlobalFunc.cxx:532

RooFit::Bins
RooCmdArg Bins(Int_t nbin)
Definition RooGlobalFunc.cxx:536

RooFit::PrintEvalErrors
RooCmdArg PrintEvalErrors(Int_t numErrors)
Definition RooGlobalFunc.cxx:727

RooFit::EvalErrorWall
RooCmdArg EvalErrorWall(bool flag)
Definition RooGlobalFunc.cxx:731

RooFit::EvalErrorValue
RooCmdArg EvalErrorValue(double value)
Definition RooGlobalFunc.cxx:273

RooFit::LineColor
RooCmdArg LineColor(TColorNumber color)
Definition RooGlobalFunc.cxx:229

RooFit::ShiftToZero
RooCmdArg ShiftToZero()
Definition RooGlobalFunc.cxx:205

RooFit
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...
Definition CodegenImpl.h:72

rf601_intminuit.nll
nll
Definition rf601_intminuit.py:42

rf606_nllerrorhandling
Definition rf606_nllerrorhandling.py:1

Range
Ta Range(0, 0, 1, 1)

m
TMarker m
Definition textangle.C:8