Namespaces
Variants
Views
Actions

std::weibull_distribution

From cppreference.com
< cpp‎ | numeric‎ | random
 
 
 
 
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.

Contents

[edit] 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.

[edit] Member types

Member type Definition
result_type (C++11) RealType
param_type (C++11) the type of the parameter set, see RandomNumberDistribution.

[edit] Member functions

constructs new distribution
(public member function) [edit]
(C++11)
resets the internal state of the distribution
(public member function) [edit]
Generation
generates the next random number in the distribution
(public member function) [edit]
Characteristics
(C++11)
returns the distribution parameters
(public member function) [edit]
(C++11)
gets or sets the distribution parameter object
(public member function) [edit]
(C++11)
returns the minimum potentially generated value
(public member function) [edit]
(C++11)
returns the maximum potentially generated value
(public member function) [edit]

[edit] Non-member functions

(C++11)(C++11)(removed in C++20)
compares two distribution objects
(function) [edit]
performs stream input and output on pseudo-random number distribution
(function template) [edit]

[edit] Example

#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <random>
#include <string>
 
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))];
 
    std::cout << std::fixed << std::setprecision(1) << std::hex;
    for (auto [x, y] : hist)
        std::cout << x << ' ' << std::string(y / 200, '*') << '\n';
}

Possible output:

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

[edit] External links

1.  Weisstein, Eric W. "Weibull Distribution." From MathWorld — A Wolfram Web Resource.
2.  Weibull distribution — From Wikipedia.