std::tr1::poisson_distribution(3)

NAME
std::tr1::poisson_distribution - A discrete Poisson random number distribution.

SYNOPSIS

  Public Types
typedef _RealType input_type
typedef _IntType result_type

  Public Member Functions
_RealType mean () const
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::tr1::poisson_distribution< _IntType, _RealType >
A discrete Poisson random number distribution. The formula for the Poisson probability mass function is $ p(i) = ac{mean^i}{i!} e^{-mean} $ where $ mean $ is the parameter of the distribution.

Definition at line 1873 of file tr1/random.h.

Member Function Documentation

  template<typename _IntType = int, typename _RealType = double> _RealType std::tr1::poisson_distribution< _IntType, _RealType >::mean () const [inline]

Gets the distribution parameter mean.

Definition at line 1893 of file tr1/random.h.

  template<typename _IntType , typename _RealType > template<class _UniformRandomNumberGenerator > poisson_distribution< _IntType, _RealType >::result_type std::tr1::poisson_distribution< _IntType, _RealType >::operator() (_UniformRandomNumberGenerator & __urng) [inline]

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 941 of file tr1/random.tcc.

References std::abs(), std::log(), and std::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:
    __os An output stream.
    __x A 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:
    __is An input stream.
    __x A poisson_distribution random number generator engine.

Returns:
    The input stream with __x extracted or in an error state.

Author

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