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

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

Non-member functions

operator==operator!=	compares two distribution objects (function)
operator<<operator>>	performs stream input and output on pseudo-random number distribution (function template)

Example

Run this code

#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

External links

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

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications

Common mathematical functions
Special mathematical functions
Floating-point environment (C++11)
Complex numbers
Numeric arrays
Pseudo-random number generation
Compile-time rational arithmetic (C++11)
Numeric algorithms
gcd (C++17)
lcm (C++17)
Generic numeric operations
iota (C++11)
accumulate
inner_product
adjacent_difference
partial_sum

Engines and engine adaptors
linear_congruential_engine (C++11)
mersenne_twister_engine (C++11)
subtract_with_carry_engine (C++11)
discard_block_engine (C++11)
independent_bits_engine (C++11)
shuffle_order_engine (C++11)
Generators
random_device (C++11)
Distributions
Uniform distributions
uniform_int_distribution (C++11)
uniform_real_distribution (C++11)
generate_canonical (C++11)
Bernoulli distributions
bernoulli_distribution (C++11)
binomial_distribution (C++11)
negative_binomial_distribution (C++11)
geometric_distribution (C++11)
Poisson distributions
poisson_distribution (C++11)
exponential_distribution (C++11)
gamma_distribution (C++11)
weibull_distribution (C++11)
extreme_value_distribution (C++11)
Normal distributions
normal_distribution (C++11)
lognormal_distribution (C++11)
chi_squared_distribution (C++11)
cauchy_distribution (C++11)
fisher_f_distribution (C++11)
student_t_distribution (C++11)
Sampling distributions
discrete_distribution (C++11)
piecewise_constant_distribution (C++11)
piecewise_linear_distribution (C++11)
Seed Sequences
seed_seq (C++11)
C library
rand
srand
RAND_MAX

Member functions
weibull_distribution::weibull_distribution
weibull_distribution::reset
Generation
weibull_distribution::operator()
Characteristics
weibull_distribution::aweibull_distribution::b
weibull_distribution::param
weibull_distribution::min
weibull_distribution::max
Non-member functions
operator==operator!=
operator<<operator>>