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std::lognormal_distribution - cppreference.com

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template< class RealType = double > class lognormal_distribution;

 (since C++11)

The lognormal_distribution random number distribution produces random numbers x > 0 according to a Log-normal distribution:

f(x; m,s) = exp⎛
⎜
⎝- ⎞
⎟
⎠

The parameters m and s are, respectively, the mean and standard deviation of the natural logarithm of x.

std::lognormal_distribution satisfies all requirements of 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 (C++11) RealType
param_type (C++11) the type of the parameter set, see RandomNumberDistribution.

Member functions

constructs new distribution
(public member function) [edit]

(C++11)

 resets the internal state of the distribution
(public member function) [edit]
Generation
generates the next random number in the distribution
(public member function) [edit]
Characteristics

(C++11)

 returns the distribution parameters
(public member function) [edit]

(C++11)

 gets or sets the distribution parameter object
(public member function) [edit]

(C++11)

 returns the minimum potentially generated value
(public member function) [edit]

(C++11)

 returns the maximum potentially generated value
(public member function) [edit]

Non-member functions

Example

#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <random>
#include <string>

int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());

    std::lognormal_distribution<> d(1.6, 0.25);
 
    std::map<int, int> hist;
    for (int n = 0; n < 1e4; ++n)
        ++hist[std::round(d(gen))];

    for (std::cout << std::fixed << std::setprecision(1); auto [x, y] : hist)
        std::cout << std::hex << x << ' ' << std::string(y / 200, '*') << '\n';
}

Possible output: 

2
3 ***
4 *************
5 ***************
6 *********
7 ****
8 *
9
a
b
c

External links