libstdc++
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std::poisson_distribution< _IntType, _RealType > Class Template Reference
Discrete Distributions

Public Types

typedef _RealType input_type
 
typedef _IntType result_type
 

Public Member Functions

_RealType mean () const
 
template<class _UniformRandomNumberGenerator >
poisson_distribution< _IntType,
_RealType >::result_type 		operator() (_UniformRandomNumberGenerator &__urng)
 
template<class _UniformRandomNumberGenerator >
result_type operator() (_UniformRandomNumberGenerator &__urng)
 
 poisson_distribution (const _RealType &__mean=_RealType(1))
 
void reset ()
 

Friends

template<typename _IntType1 , typename _RealType1 , typename _CharT , typename _Traits >
std::basic_ostream< _CharT,
_Traits > & 		operator<< (std::basic_ostream< _CharT, _Traits > &__os, const poisson_distribution< _IntType1, _RealType1 > &__x)
 
template<typename _IntType1 , typename _RealType1 , typename _CharT , typename _Traits >
std::basic_istream< _CharT,
_Traits > & 		operator>> (std::basic_istream< _CharT, _Traits > &__is, poisson_distribution< _IntType1, _RealType1 > &__x)
 

Detailed Description

template<typename _IntType = int, typename _RealType = double>
class std::poisson_distribution< _IntType, _RealType >

A discrete Poisson random number distribution.

The formula for the Poisson probability mass function is $ p(i) = \frac{mean^i}{i!} e^{-mean} $ where $ mean $ is the parameter of the distribution.

Definition at line 1864 of file tr1_impl/random.

Member Function Documentation

template<typename _IntType = int, typename _RealType = double>
_RealType std::poisson_distribution< _IntType, _RealType >::mean ( ) const
inline

Gets the distribution parameter mean.

Definition at line 1884 of file tr1_impl/random.

template<typename _IntType = int, typename _RealType = double>
template<class _UniformRandomNumberGenerator >
poisson_distribution<_IntType, _RealType>::result_type std::poisson_distribution< _IntType, _RealType >::operator() ( _UniformRandomNumberGenerator &  __urng)

A rejection algorithm when mean >= 12 and a simple method based upon the multiplication of uniform random variates otherwise. NB: The former is available only if _GLIBCXX_USE_C99_MATH_TR1 is defined.

Reference: Devroye, L. "Non-Uniform Random Variates Generation." Springer-Verlag, New York, 1986, Ch. X, Sects. 3.3 & 3.4 (+ Errata!).

Definition at line 936 of file random.tcc.

References std::abs(), std::numeric_limits< _Tp >::epsilon(), std::log(), and std::numeric_limits< _Tp >::max().

Friends And Related Function Documentation

template<typename _IntType = int, typename _RealType = double>
template<typename _IntType1 , typename _RealType1 , typename _CharT , typename _Traits >
std::basic_ostream<_CharT, _Traits>& operator<< ( std::basic_ostream< _CharT, _Traits > &  __os,
const poisson_distribution< _IntType1, _RealType1 > &  __x 
)
friend

Inserts a poisson_distribution random number distribution __x into the output stream __os.

Parameters
__osAn output stream.
__xA poisson_distribution random number distribution.
Returns
The output stream with the state of __x inserted or in an error state.
template<typename _IntType = int, typename _RealType = double>
template<typename _IntType1 , typename _RealType1 , typename _CharT , typename _Traits >
std::basic_istream<_CharT, _Traits>& operator>> ( std::basic_istream< _CharT, _Traits > &  __is,
poisson_distribution< _IntType1, _RealType1 > &  __x 
)
friend

Extracts a poisson_distribution random number distribution __x from the input stream __is.

Parameters
__isAn input stream.
__xA poisson_distribution random number generator engine.
Returns
The input stream with __x extracted or in an error state.
The documentation for this class was generated from the following files: