std::weibull_distribution
From cppreference.com
Defined in header <random>
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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
(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) |
[edit] 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) |
[edit] 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
[edit] External links
1. | Weisstein, Eric W. "Weibull Distribution." From MathWorld — A Wolfram Web Resource. |
2. | Weibull distribution — From Wikipedia. |