26 Numerics library [numerics]

26.6 Random number generation [rand]

26.6.8 Random number distribution class templates [rand.dist]

26.6.8.5 Normal distributions [rand.dist.norm]

26.6.8.5.2 Class template lognormal_distribution [rand.dist.norm.lognormal]

1

A lognormal_distribution random number distribution produces random numbers x > 0 distributed according to the probability density function\[% p(x\,|\,m,s) = \frac{1} {s x \sqrt{2 \pi}} \cdot \exp{\left(- \, \frac{(\ln{x} - m)^2} {2 s^2} \right) } \; \mbox{.} \]

template<class RealType = double>
 class lognormal_distribution{
public:
 // types
 using result_type = RealType;
 using param_type  = unspecified;

 // constructor and reset functions
 explicit lognormal_distribution(RealType m = 0.0, RealType s = 1.0);
 explicit lognormal_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
 RealType m() const;
 RealType s() const;
 param_type param() const;
 void param(const param_type& parm);
 result_type min() const;
 result_type max() const;
};

explicit lognormal_distribution(RealType m = 0.0, RealType s = 1.0);

2

Requires: 0 < s .

3

Effects: Constructs a lognormal_distribution object; m and s correspond to the respective parameters of the distribution.

RealType m() const;

4

Returns: The value of the m parameter with which the object was constructed.

RealType s() const;

5

Returns: The value of the s parameter with which the object was constructed.