26 Numerics library [numerics]

26.5 Random number generation [rand]

26.5.8 Random number distribution class templates [rand.dist]

26.5.8.5 Normal distributions [rand.dist.norm]

26.5.8.5.1 Class template normal_distribution [rand.dist.norm.normal]

1

A normal_distribution random number distribution produces random numbers x distributed according to the probability density function \[% p(x\,|\,\mu,\sigma) = {1 \over \sigma \sqrt{2\pi}} \cdot % e^{-(x-\mu)^2 / (2\sigma^2)} \exp{\left(- \, \frac{(x - \mu)^2} {2 \sigma^2} \right) } \; \mbox{.} \] The distribution parameters μ and σ are also known as this distribution's mean and standard deviation.

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

 // constructors and reset functions
 explicit normal_distribution(RealType mean = 0.0, RealType stddev = 1.0);
 explicit normal_distribution(const param_type& parm);
 void reset();

 // generating functions
 template<class URNG>
   result_type operator()(URNG& g);
 template<class URNG>
   result_type operator()(URNG& g, const param_type& parm);

 // property functions
 RealType mean() const;
 RealType stddev() const;
 param_type param() const;
 void param(const param_type& parm);
 result_type min() const;
 result_type max() const;
};

explicit normal_distribution(RealType mean = 0.0, RealType stddev = 1.0);

2

Requires: 0 < stddev .

3

Effects: Constructs a normal_distribution object; mean and stddev correspond to the respective parameters of the distribution.

RealType mean() const;

4

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

RealType stddev() const;

5

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