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RooExponential.cxx
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1/*****************************************************************************
2 * Project: RooFit *
3 * Package: RooFitModels *
4 * @(#)root/roofit:$Id$
5 * Authors: *
6 * WV, Wouter Verkerke, UC Santa Barbara, verkerke@slac.stanford.edu *
7 * DK, David Kirkby, UC Irvine, dkirkby@uci.edu *
8 * *
9 * Copyright (c) 2000-2005, Regents of the University of California *
11 * *
12 * Redistribution and use in source and binary forms, *
13 * with or without modification, are permitted according to the terms *
15 *****************************************************************************/
16
17/** \class RooExponential
18 \ingroup Roofit
19
20Exponential PDF. It computes
21\f[
22 \mathrm{RooExponential}(x, c) = \mathcal{N} \cdot \exp(c\cdot x),
23\f]
24where \f$\mathcal{N} \f$ is a normalisation constant that depends on the
25range and values of the arguments.
26**/
27
28#include "RooExponential.h"
29
30#include "RooRealVar.h"
31#include "RooBatchCompute.h"
32
33
34#include <cmath>
35
36using namespace std;
37
39
40////////////////////////////////////////////////////////////////////////////////
41
42RooExponential::RooExponential(const char *name, const char *title,
43 RooAbsReal& _x, RooAbsReal& _c) :
44 RooAbsPdf(name, title),
45 x("x","Dependent",this,_x),
46 c("c","Exponent",this,_c)
47{
48}
49
50////////////////////////////////////////////////////////////////////////////////
51
53 RooAbsPdf(other, name), x("x",this,other.x), c("c",this,other.c)
54{
55}
56
57////////////////////////////////////////////////////////////////////////////////
58///cout << "exp(x=" << x << ",c=" << c << ")=" << exp(c*x) << endl ;
59
61 return exp(c*x);
62}
63
64////////////////////////////////////////////////////////////////////////////////
65
66Int_t RooExponential::getAnalyticalIntegral(RooArgSet& allVars, RooArgSet& analVars, const char* /*rangeName*/) const
67{
68 if (matchArgs(allVars,analVars,x)) return 1;
69 if (matchArgs(allVars,analVars,c)) return 2;
70 return 0 ;
71}
72
73////////////////////////////////////////////////////////////////////////////////
74
75Double_t RooExponential::analyticalIntegral(Int_t code, const char* rangeName) const
76{
77 assert(code == 1 || code ==2);
78
79 auto& constant = code == 1 ? c : x;
80 auto& integrand = code == 1 ? x : c;
81
82 if (constant == 0.0) {
83 return integrand.max(rangeName) - integrand.min(rangeName);
84 }
85
86 return (exp(constant*integrand.max(rangeName)) - exp(constant*integrand.min(rangeName)))
87 / constant;
88}
89
90////////////////////////////////////////////////////////////////////////////////
91/// Compute multiple values of Exponential distribution.
93 return RooBatchCompute::dispatch->computeExponential(this, evalData, x->getValues(evalData, normSet), c->getValues(evalData, normSet));
94}
95
#define c(i)
Definition RSha256.hxx:101
#define ClassImp(name)
Definition Rtypes.h:364
char name[80]
Definition TGX11.cxx:110
double exp(double)
RooAbsReal is the common abstract base class for objects that represent a real value and implements f...
Definition RooAbsReal.h:61
virtual RooSpan< const double > getValues(RooBatchCompute::RunContext &evalData, const RooArgSet *normSet=nullptr) const
by this change, please consult the release notes for ROOT 6.24 for guidance on how to make this trans...
Bool_t matchArgs(const RooArgSet &allDeps, RooArgSet &numDeps, const RooArgProxy &a) const
Utility function for use in getAnalyticalIntegral().
RooArgSet is a container object that can hold multiple RooAbsArg objects.
Definition RooArgSet.h:29
virtual RooSpan< double > computeExponential(const RooAbsReal *, RunContext &, RooSpan< const double > x, RooSpan< const double > c)=0
Exponential PDF.
RooRealProxy c
Double_t analyticalIntegral(Int_t code, const char *rangeName=0) const override
Implements the actual analytical integral(s) advertised by getAnalyticalIntegral.
Int_t getAnalyticalIntegral(RooArgSet &allVars, RooArgSet &analVars, const char *rangeName=0) const override
Interface function getAnalyticalIntergral advertises the analytical integrals that are supported.
RooRealProxy x
RooSpan< double > evaluateSpan(RooBatchCompute::RunContext &evalData, const RooArgSet *normSet) const override
Compute multiple values of Exponential distribution.
Double_t evaluate() const override
cout << "exp(x=" << x << ",c=" << c << ")=" << exp(c*x) << endl ;
A simple container to hold a batch of data values.
Definition RooSpan.h:34
double max(const char *rname=0) const
Query upper limit of range. This requires the payload to be RooAbsRealLValue or derived.
Double_t x[n]
Definition legend1.C:17
R__EXTERN RooBatchComputeInterface * dispatch
This dispatch pointer points to an implementation of the compute library, provided one has been loade...
This struct enables passing computation data around between elements of a computation graph.
Definition RunContext.h:31