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RooDstD0BG.cxx
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1 /*****************************************************************************
2  * Project: RooFit *
3  * Package: RooFitModels *
4  * @(#)root/roofit:$Id$
5  * Authors: *
6  * UE, Ulrik Egede, RAL, U.Egede@rl.ac.uk *
7  * MT, Max Turri, UC Santa Cruz turri@slac.stanford.edu *
8  * CC, Chih-hsiang Cheng, Stanford chcheng@slac.stanford.edu *
9  * DK, David Kirkby, UC Irvine, dkirkby@uci.edu *
10  * *
11  * Copyright (c) 2000-2005, Regents of the University of California *
12  * RAL and Stanford University. All rights reserved.*
13  * *
14  * Redistribution and use in source and binary forms, *
15  * with or without modification, are permitted according to the terms *
16  * listed in LICENSE (http://roofit.sourceforge.net/license.txt) *
17  *****************************************************************************/
18 
19 /** \class RooDstD0BG
20  \ingroup Roofit
21 
22 Special p.d.f shape that can be used to model the background of
23 D*-D0 mass difference distributions
24 **/
25 
26 #include "RooFit.h"
27 
28 #include "Riostream.h"
29 #include "Riostream.h"
30 #include <math.h>
31 #include "TMath.h"
32 
33 #include "RooDstD0BG.h"
34 #include "RooAbsReal.h"
35 #include "RooRealVar.h"
36 #include "RooIntegrator1D.h"
37 #include "RooAbsFunc.h"
38 
39 using namespace std;
40 
42 
43 ////////////////////////////////////////////////////////////////////////////////
44 
45 RooDstD0BG::RooDstD0BG(const char *name, const char *title,
46  RooAbsReal& _dm, RooAbsReal& _dm0,
47  RooAbsReal& _c, RooAbsReal& _a, RooAbsReal& _b) :
48  RooAbsPdf(name,title),
49  dm("dm","Dstar-D0 Mass Diff",this, _dm),
50  dm0("dm0","Threshold",this, _dm0),
51  C("C","Shape Parameter",this, _c),
52  A("A","Shape Parameter 2",this, _a),
53  B("B","Shape Parameter 3",this, _b)
54 {
55 }
56 
57 ////////////////////////////////////////////////////////////////////////////////
58 
59 RooDstD0BG::RooDstD0BG(const RooDstD0BG& other, const char *name) :
60  RooAbsPdf(other,name), dm("dm",this,other.dm), dm0("dm0",this,other.dm0),
61  C("C",this,other.C), A("A",this,other.A), B("B",this,other.B)
62 {
63 }
64 
65 ////////////////////////////////////////////////////////////////////////////////
66 
68 {
69  Double_t arg= dm- dm0;
70  if (arg <= 0 ) return 0;
71  Double_t ratio= dm/dm0;
72  Double_t val= (1- exp(-arg/C))* TMath::Power(ratio, A) + B*(ratio-1);
73 
74  return (val > 0 ? val : 0) ;
75 }
76 
77 
78 ////////////////////////////////////////////////////////////////////////////////
79 /// if (matchArgs(allVars,analVars,dm)) return 1 ;
80 
81 Int_t RooDstD0BG::getAnalyticalIntegral(RooArgSet& /*allVars*/, RooArgSet& /*analVars*/, const char* /*rangeName*/) const
82 {
83  return 0 ;
84 }
85 
86 ////////////////////////////////////////////////////////////////////////////////
87 
88 Double_t RooDstD0BG::analyticalIntegral(Int_t code, const char* rangeName) const
89 {
90  switch(code) {
91  case 1:
92  {
93  Double_t min= dm.min(rangeName);
94  Double_t max= dm.max(rangeName);
95  if (max <= dm0 ) return 0;
96  else if (min < dm0) min = dm0;
97 
98  Bool_t doNumerical= kFALSE;
99  if ( A != 0 ) doNumerical= kTRUE;
100  else if (B < 0) {
101  // If b<0, pdf can be negative at large dm, the integral should
102  // only up to where pdf hits zero. Better solution should be
103  // solve the zero and use it as max.
104  // Here we check this whether pdf(max) < 0. If true, let numerical
105  // integral take care of. ( kind of ugly!)
106  if ( 1- exp(-(max-dm0)/C) + B*(max/dm0 -1) < 0) doNumerical= kTRUE;
107  }
108  if ( ! doNumerical ) {
109  return (max-min)+ C* exp(dm0/C)* (exp(-max/C)- exp(-min/C)) +
110  B * (0.5* (max*max - min*min)/dm0 - (max- min));
111  } else {
112  // In principle the integral for a!=0 can be done analytically.
113  // It involves incomplete Gamma function, TMath::Gamma(a+1,m/c),
114  // which is not defined for a < -1. And the whole expression is
115  // not stable for m/c >> 1.
116  // Do numerical integral
117  RooArgSet vset(dm.arg(),"vset");
118  RooAbsFunc *func= bindVars(vset);
119  RooIntegrator1D integrator(*func,min,max);
120  return integrator.integral();
121  }
122  }
123  }
124 
125  assert(0) ;
126  return 0 ;
127 }
static double B[]
Double_t analyticalIntegral(Int_t code, const char *rangeName=0) const
Implements the actual analytical integral(s) advertised by getAnalyticalIntegral. ...
Definition: RooDstD0BG.cxx:88
RooRealProxy dm
Definition: RooDstD0BG.h:43
int Int_t
Definition: RtypesCore.h:41
bool Bool_t
Definition: RtypesCore.h:59
Special p.d.f shape that can be used to model the background of D*-D0 mass difference distributions...
Definition: RooDstD0BG.h:26
STL namespace.
Double_t evaluate() const
Definition: RooDstD0BG.cxx:67
static double A[]
LongDouble_t Power(LongDouble_t x, LongDouble_t y)
Definition: TMath.h:628
RooRealProxy C
Definition: RooDstD0BG.h:45
RooRealProxy dm0
Definition: RooDstD0BG.h:44
RooRealProxy A
Definition: RooDstD0BG.h:45
static double C[]
virtual Double_t integral(const Double_t *yvec=0)
Calculate numeric integral at given set of function binding parameters.
const Bool_t kFALSE
Definition: RtypesCore.h:92
RooIntegrator1D implements an adaptive one-dimensional numerical integration algorithm.
#define ClassImp(name)
Definition: Rtypes.h:336
Double_t min(const char *rname=0) const
Definition: RooRealProxy.h:56
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
RooAbsFunc * bindVars(const RooArgSet &vars, const RooArgSet *nset=0, Bool_t clipInvalid=kFALSE) const
Create an interface adaptor f(vars) that binds us to the specified variables (in arbitrary order)...
RooRealProxy B
Definition: RooDstD0BG.h:45
double func(double *x, double *p)
Definition: stressTF1.cxx:213
Int_t getAnalyticalIntegral(RooArgSet &allVars, RooArgSet &analVars, const char *rangeName=0) const
if (matchArgs(allVars,analVars,dm)) return 1 ;
Definition: RooDstD0BG.cxx:81
Double_t max(const char *rname=0) const
Definition: RooRealProxy.h:57
RooAbsPdf is the abstract interface for all probability density functions The class provides hybrid a...
Definition: RooAbsPdf.h:41
const RooAbsReal & arg() const
Definition: RooRealProxy.h:43
double exp(double)
const Bool_t kTRUE
Definition: RtypesCore.h:91
Abstract interface for evaluating a real-valued function of one real variable and performing numerica...
Definition: RooAbsFunc.h:23