std::weibull_distribution
From cppreference.com
| 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:
- {{mathjax-or|1=\(\small{f(x;a,b)=\frac{a}{b}{(\frac{x}{b})}^{a-1}\exp{(-{(\frac{x}{b})}^{a})} }\)|2=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 (C++11)
|
RealType
|
param_type (C++11)
|
the type of the parameter set, see RandomNumberDistribution. |
Member functions
(C++11) |
constructs new distribution (public member function) |
(C++11) |
resets the internal state of the distribution (public member function) |
Generation | |
(C++11) |
generates the next random number in the distribution (public member function) |
Characteristics | |
(C++11) |
returns the distribution parameters (public member function) |
(C++11) |
gets or sets the distribution parameter object (public member function) |
(C++11) |
returns the minimum potentially generated value (public member function) |
(C++11) |
returns the maximum potentially generated value (public member function) |
Non-member functions
(C++11)(C++11)(removed in C++20) |
compares two distribution objects (function) |
(C++11) |
performs stream input and output on pseudo-random number distribution (function template) |
Example
Run this code
#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
External links
| 1. | Weisstein, Eric W. "Weibull Distribution." From MathWorld — A Wolfram Web Resource. |
| 2. | Weibull distribution — From Wikipedia. |
