# 28 Numerics library [numerics]

## 28.5 Random number generation [rand]

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

#### 28.5.9.5.2 Class template lognormal_distribution[rand.dist.norm.lognormal]

A lognormal_distribution random number distribution produces random numbers distributed according to the probability density function in Formula 28.14.
namespace std { template<class RealType = double> class lognormal_distribution { public: // types using result_type = RealType; using param_type = unspecified; // constructor and reset functions lognormal_distribution() : lognormal_distribution(0.0) {} explicit lognormal_distribution(RealType m, RealType s = 1.0); explicit lognormal_distribution(const param_type& parm); void reset(); // equality operators friend bool operator==(const lognormal_distribution& x, const lognormal_distribution& y); // generating functions template<class URBG> result_type operator()(URBG& g); template<class URBG> result_type operator()(URBG& g, const param_type& parm); // property functions RealType m() const; RealType s() const; param_type param() const; void param(const param_type& parm); result_type min() const; result_type max() const; // inserters and extractors template<class charT, class traits> friend basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const lognormal_distribution& x); template<class charT, class traits> friend basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>& is, lognormal_distribution& x); }; }
explicit lognormal_distribution(RealType m, RealType s = 1.0);
Preconditions: .
Remarks: m and s correspond to the respective parameters of the distribution.
RealType m() const;
Returns: The value of the m parameter with which the object was constructed.
RealType s() const;
Returns: The value of the s parameter with which the object was constructed.