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std::normal_distribution - cppreference.com

From cppreference.com

template< class RealType = double > class normal_distribution;

 (since C++11)

Generates random numbers according to the Normal (or Gaussian) random number distribution. It is defined as:

f(x; μ,σ) = exp⎛
⎜
⎝ ⎛
⎜
⎝⎞
⎟
⎠2
⎞
⎟
⎠

Here μ is the Mean and σ is the Standard deviation (stddev).

std::normal_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
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()};

    // Values near the mean are the most likely. Standard deviation
    // affects the dispersion of generated values from the mean.
    std::normal_distribution d{5.0, 2.0};

    // Draw a sample from the normal distribution and round it to an integer.
    auto random_int = [&d, &gen]{ return std::lround(d(gen)); };

    std::map<long, unsigned> histogram{};
    for (auto n{10000}; n; --n)
        ++histogram[random_int()];

    for (const auto [k, v] : histogram)
        std::cout << std::setw(2) << k << ' ' << std::string(v / 200, '*') << '\n';
}

Possible output: 

-1
 0
 1 *
 2 ***
 3 *****
 4 ********
 5 *********
 6 *********
 7 ******
 8 ***
 9 *
10
11

External links