std::tr1::poisson_distribution3cxx
A discrete poisson random number distribution.
Usage
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 1864 of file tr1_impl/random.
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 1884 of file tr1_impl/random.
template<typename _IntType , typename _RealType > template<class _UniformRandomNumberGenerator > poisson_distribution< _IntType, _RealType >::result_type std::tr1::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::log(), and std::max().