std::weibull_distribution

template <class RealType = double> class weibull_distribution;

Weibull distribution

Random number distribution that produces floating-point values according to a 2-parameter Weibull distribution, which is described by the following probability density function:

This distribution produces random numbers where each value can be interpreted -in terms of population- as the lifetime for which the death probability is proportional to the a-th power of time. Parameter b scales the process.

The distribution parameters, a and b, are set on construction.

To produce a random value following this distribution, call its member function operator().

Template parameters

RealType: A floating-point type. Aliased as member type result_type.
By default, this is double.

Member types

The following aliases are member types of weibull_distribution:

member type	definition	notes
`result_type`	The first template parameter (`RealType`)	The type of the numbers generated (defaults to `double`)
`param_type`	not specified	The type returned by member param.

Member functions

(constructor): Construct Weibull distribution (public member function)

operator(): Generate random number (public member function)

reset: Reset distribution (public member function)

param: Distribution parameters (public member function)

min: Minimum value (public member function)

max: Maximum value (public member function)

Distribution parameters:

a: Parameter a (public member function)

b: Parameter b (public member function)

Non-member functions

operator<<: Insert into output stream (function template)

operator>>: Extract from input stream (function template)

relational operators: Relational operators (function template)

Example

// weibull_distribution
#include <iostream>
#include <random>

int main()
{
  const int nrolls=10000;  // number of experiments
  const int nstars=100;    // maximum number of stars to distribute

  std::default_random_engine generator;
  std::weibull_distribution<double> distribution(2.0,4.0);

  int p[10]={};

  for (int i=0; i<nrolls; ++i) {
    double number = distribution(generator);
    if (number<10) ++p[int(number)];
  }

  std::cout << "weibull_distribution (2.0,4.0):" << std::endl;

  for (int i=0; i<10; ++i) {
    std::cout << i << "-" << (i+1) << ": ";
    std::cout << std::string(p[i]*nstars/nrolls,'*') << std::endl;
  }

  return 0;
}

Possible output:

weibull_distribution (2.0,4.0):
0-1: ******
1-2: ***************
2-3: *********************
3-4: ********************
4-5: ***************
5-6: ***********
6-7: *****
7-8: **
8-9: *
9-10:

distributions

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member functions

non-member functions