std::gamma_distribution(3)std::gamma_distribution(3)NAMEstd::gamma_distribution-
A gamma continuous distribution for random numbers.
SYNOPSIS
Public Types
typedef _RealType input_type
typedef _RealType result_type
Public Member Functions
_RealType alpha () const
gamma_distribution (const result_type &__alpha_val=result_type(1))
template<class _UniformRandomNumberGenerator > result_type operator()
(_UniformRandomNumberGenerator &__urng)
void reset ()
Friends
template<typename _RealType1 , typename _CharT , typename _Traits >
std::basic_ostream< _CharT, _Traits > & operator<<
(std::basic_ostream< _CharT, _Traits > &__os, const
gamma_distribution< _RealType1 > &__x)
template<typename _CharT , typename _Traits > std::basic_istream<
_CharT, _Traits > & operator>> (std::basic_istream< _CharT, _Traits
> &__is, gamma_distribution &__x)
Detailed Description
template<typename _RealType = double> class std::gamma_distribution<
_RealType >
A gamma continuous distribution for random numbers.
The formula for the gamma probability mass function is $ p(x) =
ac{1}{Gamma(lpha)} x^{lpha - 1} e^{-x} $.
Definition at line 2320 of file tr1_impl/random.
Constructor & Destructor Documentation
template<typename _RealType = double> std::gamma_distribution< _RealType
>::gamma_distribution (const result_type & __alpha_val =
result_type(1)) [inline, explicit] Constructs a gamma distribution with
parameters $ ...lpha $.
Definition at line 2332 of file tr1_impl/random.
Member Function Documentation
template<typename _RealType = double> _RealType std::gamma_distribution<
_RealType >::alpha () const [inline] Gets the $ .....lpha $ of the
distribution.
Definition at line 2343 of file tr1_impl/random.
template<typename _RealType > template<class _UniformRandomNumberGenerator
> gamma_distribution< _RealType >::result_type std::gamma_distribution<
_RealType >::operator() (_UniformRandomNumberGenerator & __urng)
[inline] Cheng's rejection algorithm GB for alpha >= 1 and a
modification of Vaduva's rejection from Weibull algorithm due to
Devroye for alpha < 1.
References: Cheng, R. C. 'The Generation of Gamma Random Variables with
Non-integral
Shape Parameter.' Applied Statistics, 26, 71-75, 1977.
Vaduva, I. 'Computer Generation of Gamma Gandom Variables by Rejection
and Composition Procedures.' Math. Operationsforschung and Statistik,
Series in Statistics, 8, 545-576, 1977.
Devroye, L. 'Non-Uniform Random Variates Generation.' Springer-Verlag,
New York, 1986, Ch. IX, Sect. 3.4 (+ Errata!).
Definition at line 1501 of file random.tcc.
References std::exp(), std::log(), and std::pow().
template<typename _RealType = double> void std::gamma_distribution<
_RealType >::reset () [inline] Resets the distribution.
Definition at line 2350 of file tr1_impl/random.
Friends And Related Function Documentation
template<typename _RealType = double> template<typename _RealType1 ,
typename _CharT , typename _Traits > std::basic_ostream<_CharT,
_Traits>& operator<< (std::basic_ostream< _CharT, _Traits > & __os,
const gamma_distribution< _RealType1 > & __x) [friend] Inserts a
gamma_distribution random number distribution __x into the output
stream __os.
Parameters:
__os An output stream.
__x A gamma_distribution random number distribution.
Returns:
The output stream with the state of __x inserted or in an error
state.
template<typename _RealType = double> template<typename _CharT , typename
_Traits > std::basic_istream<_CharT, _Traits>& operator>>
(std::basic_istream< _CharT, _Traits > & __is, gamma_distribution<
_RealType > & __x) [friend] Extracts a gamma_distribution random number
distribution __x from the input stream __is.
Parameters:
__is An input stream.
__x A gamma_distribution random number generator engine.
Returns:
The input stream with __x extracted or in an error state.
Definition at line 2382 of file tr1_impl/random.
Author
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libstdc++ 22 Nov 2013 std::gamma_distribution(3)
