# 26 Numerics library [numerics]

## 26.6 Random number generation [rand]

### 26.6.9 Random number distribution class templates [rand.dist]

#### 26.6.9.3.1 Class bernoulli_­distribution[rand.dist.bern.bernoulli]

A bernoulli_­distribution random number distribution produces bool values b distributed according to the discrete probability function
class bernoulli_distribution { public: // types using result_type = bool; using param_type = unspecified; // constructors and reset functions bernoulli_distribution() : bernoulli_distribution(0.5) {} explicit bernoulli_distribution(double p); explicit bernoulli_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 double p() const; param_type param() const; void param(const param_type& parm); result_type min() const; result_type max() const; };
```explicit bernoulli_distribution(double p); ```
Preconditions: .
Remarks: p corresponds to the parameter of the distribution.
```double p() const; ```
Returns: The value of the p parameter with which the object was constructed.

#### 26.6.9.3.2 Class template binomial_­distribution[rand.dist.bern.bin]

A binomial_­distribution random number distribution produces integer values distributed according to the discrete probability function
template<class IntType = int> class binomial_distribution { public: // types using result_type = IntType; using param_type = unspecified; // constructors and reset functions binomial_distribution() : binomial_distribution(1) {} explicit binomial_distribution(IntType t, double p = 0.5); explicit 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 t() const; double p() const; param_type param() const; void param(const param_type& parm); result_type min() const; result_type max() const; };
```explicit binomial_distribution(IntType t, double p = 0.5); ```
Preconditions: and .
Remarks: t and p correspond to the respective parameters of the distribution.
```IntType t() const; ```
Returns: The value of the t parameter with which the object was constructed.
```double p() const; ```
Returns: The value of the p parameter with which the object was constructed.

#### 26.6.9.3.3 Class template geometric_­distribution[rand.dist.bern.geo]

A geometric_­distribution random number distribution produces integer values distributed according to the discrete probability function
template<class IntType = int> class geometric_distribution { public: // types using result_type = IntType; using param_type = unspecified; // constructors and reset functions geometric_distribution() : geometric_distribution(0.5) {} explicit geometric_distribution(double p); explicit geometric_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 double p() const; param_type param() const; void param(const param_type& parm); result_type min() const; result_type max() const; };
```explicit geometric_distribution(double p); ```
Preconditions: .
Remarks: p corresponds to the parameter of the distribution.
```double p() const; ```
Returns: The value of the p parameter with which the object was constructed.

#### 26.6.9.3.4 Class template negative_­binomial_­distribution[rand.dist.bern.negbin]

A negative_­binomial_­distribution random number distribution produces random integers distributed according to the discrete probability function
[Note 1:
This implies that 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 negative_binomial_distribution() : negative_binomial_distribution(1) {} explicit negative_binomial_distribution(IntType k, 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, double p = 0.5); ```
Preconditions: and .
Remarks: k and p correspond to the respective parameters of the distribution.
```IntType k() const; ```
Returns: The value of the k parameter with which the object was constructed.
```double p() const; ```
Returns: The value of the p parameter with which the object was constructed.