26 Numerics library [numerics]
26.6 Random number generation [rand]
26.6.8 Random number distribution class templates [rand.dist]
26.6.8.3 Bernoulli distributions [rand.dist.bern]
26.6.8.3.4 Class template negative_binomial_distribution [rand.dist.bern.negbin]
A negative_binomial_distribution random number distribution
produces random integers i ≥ 0
distributed according to
the discrete probability function
![\[%
P(i\,|\,k,p)
= \binom{k+i-1}{i} \cdot p^k \cdot (1-p)^i
\; \mbox{.}
\]](math/7350092705052863326.png)
[ Note:
This implies that P(i | k,p) is undefined when p == 1.
— end note ]
template<class IntType = int>
class negative_binomial_distribution{
public:
// types
using result_type = IntType;
using param_type = unspecified;
// constructor and reset functions
explicit negative_binomial_distribution(IntType k = 1, double p = 0.5);
explicit negative_binomial_distribution(const param_type& parm);
void reset();
// generating functions
template<class URBG>
result_type operator()(URBG& g);
template<class URBG>
result_type operator()(URBG& g, const param_type& parm);
// property functions
IntType k() const;
double p() const;
param_type param() const;
void param(const param_type& parm);
result_type min() const;
result_type max() const;
};
explicit negative_binomial_distribution(IntType k = 1, double p = 0.5);
Requires: 0 < p ≤ 1 and 0 < k .
Effects: Constructs a negative_binomial_distribution object; k and p correspond to the respective parameters of the distribution.
Returns: The value of the k parameter with which the object was constructed.
Returns: The value of the p parameter with which the object was constructed.