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Reference Guide
rf110_normintegration.C File Reference

Detailed Description

View in nbviewer Open in SWAN Basic functionality: normalization and integration of p.d.fs, construction of cumulative distribution monodimensional functions

RooFit v3.60 -- Developed by Wouter Verkerke and David Kirkby
Copyright (C) 2000-2013 NIKHEF, University of California & Stanford University
All rights reserved, please read http://roofit.sourceforge.net/license.txt
gx = 0.800737
gx_Norm[x] = 0.106896
gx_Int[x] = 7.49084
[#1] INFO:Eval -- RooRealVar::setRange(x) new range named 'signal' created with bounds [-5,5]
gx_Int[x|signal]_Norm[x] = 0.834753
#include "RooRealVar.h"
#include "RooGaussian.h"
#include "RooConstVar.h"
#include "RooAbsReal.h"
#include "RooPlot.h"
#include "TCanvas.h"
#include "TAxis.h"
using namespace RooFit;
// S e t u p m o d e l
// ---------------------
// Create observables x,y
RooRealVar x("x", "x", -10, 10);
// Create p.d.f. gaussx(x,-2,3)
RooGaussian gx("gx", "gx", x, RooConst(-2), RooConst(3));
// 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
// --------------------------------------------------------------------------------------------------
// Return 'raw' unnormalized value of gx
cout << "gx = " << gx.getVal() << endl;
// Return value of gx normalized over x in range [-10,10]
RooArgSet nset(x);
cout << "gx_Norm[x] = " << gx.getVal(&nset) << endl;
// Create object representing integral over gx
// which is used to calculate gx_Norm[x] == gx / gx_Int[x]
RooAbsReal *igx = gx.createIntegral(x);
cout << "gx_Int[x] = " << igx->getVal() << endl;
// 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
// ----------------------------------------------------------------------------
// Define a range named "signal" in x from -5,5
x.setRange("signal", -5, 5);
// Create an integral of gx_Norm[x] over x in range "signal"
// This is the fraction of of p.d.f. gx_Norm[x] which is in the
// range named "signal"
RooAbsReal *igx_sig = gx.createIntegral(x, NormSet(x), Range("signal"));
cout << "gx_Int[x|signal]_Norm[x] = " << igx_sig->getVal() << endl;
// 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
// -----------------------------------------------------------------------------------------------------
// Create the cumulative distribution function of gx
// i.e. calculate Int[-10,x] gx(x') dx'
RooAbsReal *gx_cdf = gx.createCdf(x);
// Plot cdf of gx versus x
RooPlot *frame = x.frame(Title("c.d.f of Gaussian p.d.f"));
// Draw plot on canvas
new TCanvas("rf110_normintegration", "rf110_normintegration", 600, 600);
07/2008 - Wouter Verkerke

Definition in file rf110_normintegration.C.