std::extreme_value_distribution

template <class RealType = double> class extreme_value_distribution;

Extreme Value distribution

Random number distribution that produces floating-point values according to a Type I extreme value distribution, which is described by the following probability density function:

This distribution produces random numbers where each value can be interpreted as the extreme (maximum or minimum) of a number of samples of a random variable.

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 extreme_value_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 extreme value 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

// extreme_value_distribution
#include <iostream>
#include <random>

int main()
{
  const int nrolls=10000;  // number of experiments
  const int nstars=100;    // maximum number of stars to distribute
  const int nintervals=20; // number of intervals
  const int first=-5;      // first interval

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

  int p[nintervals]={};

  for (int i=0; i<nrolls; ++i) {
    double number = distribution(generator);
    if ((number>=-5.0)&&(number<15.0)) ++p[int(number-first)];
  }

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

  for (int i=0; i<nintervals; ++i) {
    std::cout.width(2); std::cout << float(first+i) << "..";
    std::cout.width(2); std::cout << float(first+i+1) << ": ";
    std::cout << std::string(p[i]*nstars/nrolls,'*') << std::endl;
  }

  return 0;
}

Possible output:

extreme_value_distribution (2.0,4.0):
-5..-4: 
-4..-3: *
-3..-2: ***
-2..-1: *****
-1.. 0: *******
 0.. 1: ********
 1.. 2: ********
 2.. 3: *********
 3.. 4: ********
 4.. 5: ********
 5.. 6: ******
 6.. 7: *****
 7.. 8: *****
 8.. 9: ***
 9..10: ***
10..11: **
11..12: **
12..13: *
13..14: *
14..15: *

distributions

generators

other

member functions

non-member functions