class template
<random>

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 typedefinitionnotes
result_typeThe first template parameter (RealType)The type of the numbers generated (defaults to double)
param_typenot specifiedThe 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

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
 
// 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: *

See also

exponential_distribution
Exponential distribution (class template )
weibull_distribution
Weibull distribution (class template )
uniform_real_distribution
Uniform real distribution (class template )

C++