std::weibull_distribution

Defined in header <random> 
template< class RealType = double >
class weibull_distribution;
 (since C++11)

The weibull_distribution meets the requirements of a RandomNumberDistribution and produces random numbers according to the Weibull distribution: f(x;a,b) =

a
b
 ⎛
⎜
⎝
x
b
⎞
⎟
⎠a-1
 exp⎛
⎜
⎝-⎛
⎜
⎝
x
b
⎞
⎟
⎠a
⎞
⎟
⎠

a is the shape parameter and b the scale parameter.

std::weibull_distribution satisfies RandomNumberDistribution.

Template parameters

RealType - The result type generated by the generator. The effect is undefined if this is not one of float, double, or long double.

Member types

Member type Definition
result_type RealType
param_type the type of the parameter set, see RandomNumberDistribution.

Member functions

constructs new distribution
(public member function)
resets the internal state of the distribution
(public member function)
Generation
generates the next random number in the distribution
(public member function)
Characteristics
returns the distribution parameters
(public member function)
gets or sets the distribution parameter object
(public member function)
returns the minimum potentially generated value
(public member function)
returns the maximum potentially generated value
(public member function)

Non-member functions

compares two distribution objects
(function)
performs stream input and output on pseudo-random number distribution
(function template)

Example

#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
#include <cmath>
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
 
    std::weibull_distribution<> d;
 
    std::map<int, int> hist;
    for(int n=0; n<10000; ++n) {
        ++hist[std::round(d(gen))];
    }
    for(auto p : hist) {
        std::cout << std::fixed << std::setprecision(1) << std::setw(2)
                  << p.first << ' ' << std::string(p.second/200, '*') << '\n';
    }
}

Output:

0 *******************
 1 *******************
 2 ******
 3 **
 4 
 5 
 6 
 7 
 8

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/numeric/random/weibull_distribution