libstdc++
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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) |
A discrete Poisson random number distribution.
The formula for the Poisson probability mass function is where
is the parameter of the distribution.
Definition at line 1864 of file tr1_impl/random.
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inline |
Gets the distribution parameter mean
.
Definition at line 1884 of file tr1_impl/random.
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::log(), and std::max().
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friend |
Inserts a poisson_distribution random number distribution __x
into the output stream __os
.
__os | An output stream. |
__x | A poisson_distribution random number distribution. |
__x
inserted or in an error state.
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friend |
Extracts a poisson_distribution random number distribution __x
from the input stream __is
.
__is | An input stream. |
__x | A poisson_distribution random number generator engine. |
__x
extracted or in an error state.