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Reference Guide
RooVoigtian.cxx
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2  * Project: RooFit *
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6  * TS, Thomas Schietinger, SLAC, schieti@slac.stanford.edu *
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15 
16 /** \class RooVoigtian
17  \ingroup Roofit
18 
19 RooVoigtian is an efficient implementation of the convolution of a
20 Breit-Wigner with a Gaussian, making use of the complex error function.
21 RooFitCore provides two algorithms for the evaluation of the complex error
22 function (the default CERNlib C335 algorithm, and a faster, look-up-table
23 based method). By default, RooVoigtian employs the default (CERNlib)
24 algorithm. Select the faster algorithm either in the constructor, or with
25 the selectFastAlgorithm() method.
26 **/
27 
28 #include <cmath>
29 #include <complex>
30 
31 #include "RooFit.h"
32 
33 #include "Riostream.h"
34 
35 #include "RooVoigtian.h"
36 #include "RooAbsReal.h"
37 #include "RooRealVar.h"
38 #include "RooMath.h"
39 
40 using namespace std;
41 
43 
44 ////////////////////////////////////////////////////////////////////////////////
45 
46 RooVoigtian::RooVoigtian(const char *name, const char *title,
47  RooAbsReal& _x, RooAbsReal& _mean,
48  RooAbsReal& _width, RooAbsReal& _sigma,
49  Bool_t doFast) :
50  RooAbsPdf(name,title),
51  x("x","Dependent",this,_x),
52  mean("mean","Mean",this,_mean),
53  width("width","Breit-Wigner Width",this,_width),
54  sigma("sigma","Gauss Width",this,_sigma),
55  _doFast(doFast)
56 {
57  _invRootPi= 1./sqrt(atan2(0.,-1.));
58 }
59 
60 ////////////////////////////////////////////////////////////////////////////////
61 
62 RooVoigtian::RooVoigtian(const RooVoigtian& other, const char* name) :
63  RooAbsPdf(other,name), x("x",this,other.x), mean("mean",this,other.mean),
64  width("width",this,other.width),sigma("sigma",this,other.sigma),
65  _doFast(other._doFast)
66 {
67  _invRootPi= 1./sqrt(atan2(0.,-1.));
68 }
69 
70 ////////////////////////////////////////////////////////////////////////////////
71 
73 {
74  Double_t s = (sigma>0) ? sigma : -sigma ;
75  Double_t w = (width>0) ? width : -width ;
76 
77  Double_t coef= -0.5/(s*s);
78  Double_t arg = x - mean;
79 
80  // return constant for zero width and sigma
81  if (s==0. && w==0.) return 1.;
82 
83  // Breit-Wigner for zero sigma
84  if (s==0.) return (1./(arg*arg+0.25*w*w));
85 
86  // Gauss for zero width
87  if (w==0.) return exp(coef*arg*arg);
88 
89  // actual Voigtian for non-trivial width and sigma
90  Double_t c = 1./(sqrt(2.)*s);
91  Double_t a = 0.5*c*w;
92  Double_t u = c*arg;
93  std::complex<Double_t> z(u,a) ;
94  std::complex<Double_t> v(0.) ;
95 
96  if (_doFast) {
98  } else {
99  v = RooMath::faddeeva(z);
100  }
101  return c*_invRootPi*v.real();
102 
103 }
RooRealProxy mean
Definition: RooVoigtian.h:45
Double_t _invRootPi
Definition: RooVoigtian.h:53
Bool_t _doFast
Definition: RooVoigtian.h:54
bool Bool_t
Definition: RtypesCore.h:59
TArc * a
Definition: textangle.C:12
RooRealProxy width
Definition: RooVoigtian.h:46
STL namespace.
double sqrt(double)
Double_t x[n]
Definition: legend1.C:17
static std::complex< double > faddeeva(std::complex< double > z)
evaluate Faddeeva function for complex argument
Definition: RooMath.cxx:542
const Double_t sigma
static std::complex< double > faddeeva_fast(std::complex< double > z)
evaluate Faddeeva function for complex argument (fast version)
Definition: RooMath.cxx:549
SVector< double, 2 > v
Definition: Dict.h:5
Double_t Mean(Long64_t n, const T *a, const Double_t *w=0)
Definition: TMath.h:973
#define ClassImp(name)
Definition: Rtypes.h:336
double Double_t
Definition: RtypesCore.h:55
RooAbsReal is the common abstract base class for objects that represent a real value and implements f...
Definition: RooAbsReal.h:53
double atan2(double, double)
Double_t evaluate() const
Definition: RooVoigtian.cxx:72
static std::shared_ptr< std::function< double(double)> > Gauss
Definition: NeuralNet.icc:76
you should not use this method at all Int_t Int_t z
Definition: TRolke.cxx:630
RooAbsPdf is the abstract interface for all probability density functions The class provides hybrid a...
Definition: RooAbsPdf.h:41
RooRealProxy sigma
Definition: RooVoigtian.h:47
double exp(double)
RooRealProxy x
Definition: RooVoigtian.h:44
RooVoigtian is an efficient implementation of the convolution of a Breit-Wigner with a Gaussian...
Definition: RooVoigtian.h:24