ROOT   Reference Guide
VavilovAccuratePdf.h
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1// @(#)root/mathmore:$Id$
2// Authors: B. List 29.4.2010
3
4 /**********************************************************************
5 * *
6 * Copyright (c) 2004 ROOT Foundation, CERN/PH-SFT *
7 * *
8 * This library is free software; you can redistribute it and/or *
9 * modify it under the terms of the GNU General Public License *
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13 * This library is distributed in the hope that it will be useful, *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
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16 * General Public License for more details. *
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24
25// Header file for class VavilovAccuratePdf
26//
27// Created by: blist at Thu Apr 29 11:19:00 2010
28//
29// Last update: Thu Apr 29 11:19:00 2010
30//
31#ifndef ROOT_Math_VavilovAccuratePdf
32#define ROOT_Math_VavilovAccuratePdf
33
34
35#include "Math/IParamFunction.h"
37
38namespace ROOT {
39namespace Math {
40
41//____________________________________________________________________________
42/**
43 Class describing the Vavilov pdf.
44
45 The probability density function of the Vavilov distribution
46 is given by:
47 \f[ p(\lambda; \kappa, \beta^2) =
48 \frac{1}{2 \pi i}\int_{c-i\infty}^{c+i\infty} \phi(s) e^{\lambda s} ds\f]
49 where \f$\phi(s) = e^{C} e^{\psi(s)}\f$
50 with \f$C = \kappa (1+\beta^2 \gamma )\f$
51 and \f[\psi(s) = s \ln \kappa + (s+\beta^2 \kappa)
52 \cdot \left ( \int \limits_{0}^{1}
53 \frac{1 - e^{\frac{-st}{\kappa}}}{t} \, dt- \gamma \right )
54 - \kappa \, e^{\frac{-s}{\kappa}}\f].
55 \f$\gamma = 0.5772156649\dots\f$ is Euler's constant.
56
57 The parameters are:
58 - 0: Norm: Normalization constant
59 - 1: x0: Location parameter
60 - 2: xi: Width parameter
61 - 3: kappa: Parameter \f$\kappa\f$ of the Vavilov distribution
62 - 4: beta2: Parameter \f$\beta^2\f$ of the Vavilov distribution
63
64 Benno List, June 2010
65
66 @ingroup StatFunc
67 */
68
69
71 public:
72
73 /**
74 Default constructor
75 */
77
78 /**
79 Constructor with parameter values
80 @param p vector of doubles containing the parameter values (Norm, x0, xi, kappa, beta2).
81 */
82 VavilovAccuratePdf (const double *p);
83
84 /**
85 Destructor
86 */
87 virtual ~VavilovAccuratePdf ();
88
89 /**
90 Access the parameter values
91 */
92 virtual const double * Parameters() const;
93
94 /**
95 Set the parameter values
96
97 @param p vector of doubles containing the parameter values (Norm, x0, xi, kappa, beta2).
98
99 */
100 virtual void SetParameters(const double * p );
101
102 /**
103 Return the number of Parameters
104 */
105 virtual unsigned int NPar() const;
106
107 /**
108 Return the name of the i-th parameter (starting from zero)
109 */
110 virtual std::string ParameterName(unsigned int i) const;
111
112 /**
113 Evaluate the function
114
115 @param x The Landau parameter \f$x = \lambda_L\f$
116 */
117 virtual double DoEval(double x) const;
118
119 /**
120 Evaluate the function, using parameters p
121
122 @param x The Landau parameter \f$x = \lambda_L\f$
123 @param p vector of doubles containing the parameter values (Norm, x0, xi, kappa, beta2).
124 */
125 virtual double DoEvalPar(double x, const double * p) const;
126
127 /**
128 Return a clone of the object
129 */
130 virtual IBaseFunctionOneDim * Clone() const;
131
132 private:
133 double fP[5];
134
135};
136
137
138} // namespace Math
139} // namespace ROOT
140
141#endif /* ROOT_Math_VavilovAccuratePdf */
Interface (abstract class) for generic functions objects of one-dimension Provides a method to evalua...
Definition: IFunction.h:135
Specialized IParamFunction interface (abstract class) for one-dimensional parametric functions It is ...
Class describing the Vavilov pdf.
virtual ~VavilovAccuratePdf()
Destructor.
virtual double DoEvalPar(double x, const double *p) const
Evaluate the function, using parameters p.
virtual std::string ParameterName(unsigned int i) const
Return the name of the i-th parameter (starting from zero)
virtual void SetParameters(const double *p)
Set the parameter values.
virtual IBaseFunctionOneDim * Clone() const
Return a clone of the object.
VavilovAccuratePdf()
Default constructor.
virtual const double * Parameters() const
Access the parameter values.
virtual double DoEval(double x) const
Evaluate the function.
virtual unsigned int NPar() const
Return the number of Parameters.
Double_t x[n]
Definition: legend1.C:17
Namespace for new Math classes and functions.
VSD Structures.
Definition: StringConv.hxx:21