26 Numerics library [numerics]

26.5 Random number generation [rand]

26.5.8 Random number distribution class templates [rand.dist]

26.5.8.4 Poisson distributions [rand.dist.pois]

26.5.8.4.4 Class template weibull_distribution [rand.dist.pois.weibull]

1

A weibull_distribution random number distribution produces random numbers x ≥ 0 distributed according to the probability density function \[% p(x\,|\,a,b) = \frac{a}{b} \cdot \left(\frac{x}{b}\right)^{a-1} \cdot \, \exp\left( -\left(\frac{x}{b}\right)^a\right) \; \mbox{.} \]

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

 // constructor and reset functions
 explicit weibull_distribution(RealType a = 1.0, RealType b = 1.0);
 explicit weibull_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 a() const;
 RealType b() const;
 param_type param() const;
 void param(const param_type& parm);
 result_type min() const;
 result_type max() const;
};

explicit weibull_distribution(RealType a = 1.0, RealType b = 1.0);

2

Requires: 0 < a and 0 < b .

3

Effects: Constructs a weibull_distribution object; a and b correspond to the respective parameters of the distribution.

RealType a() const;

4

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

RealType b() const;

5

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