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: \(\small{f(x;a,b)=\frac{a}{b}{(\frac{x}{b})}^{a-1}\exp{(-{(\frac{x}{b})}^{a})} }\)f(x;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(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 |
|
| 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
#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';
}
}
Possible output:
0 ******************* 1 ******************* 2 ****** 3 ** 4 5 6 7 8
External links
- Weisstein, Eric W. "Weibull Distribution." From MathWorld--A Wolfram Web Resource.
- Weibull distribution. From Wikipedia.
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