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std::normal_distribution – cppreference.com

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definiert in Header

<random>

template< class RealType = double > class normal_distribution;

 (seit C++11)

Normal (oder Guassian) Zufallszahl Verteilung:

f(x; μ,σ) = None exp⎛
⎜
⎝- ⎛
⎜
⎝⎞
⎟
⎠2
⎞
⎟
⎠

Mit dem bedeuten μ und die Standardabweichung ( stddev) σ .

Original:

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Mitglied Typen

Mitglied Typ

Original:

Member type

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 Definition
result_type RealType
param_type

die Art des Parametersatzes, nicht näher bezeichnet

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the type of the parameter set, unspecified

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Member-Funktionen

erzeugt eine neue Verteilung
(öffentliche Elementfunktion) [edit]

setzt den internen Zustand der Verteilung

Original:

resets the internal state of the distribution

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(öffentliche Elementfunktion) [edit]

Generation

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Generation

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erzeugt das nächste Zufallszahl in der Verteilung

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generates the next random number in the distribution

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(öffentliche Elementfunktion) [edit]

Merkmale

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Characteristics

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gibt den Mittelwert (μ) Verteilung Parameter

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returns the mean (μ) distribution parameter

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(öffentliche Elementfunktion) [edit]

gibt die Standardabweichung (σ) Verteilung Parameter

Original:

returns the standard deviation (σ) distribution parameter

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(öffentliche Elementfunktion) [edit]

ab oder legt die Verteilung Parameter-Objekt

Original:

gets or sets the distribution parameter object

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(öffentliche Elementfunktion) [edit]

gibt das Minimum potentiell generierten Wert

Original:

returns the minimum potentially generated value

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(öffentliche Elementfunktion) [edit]

gibt die maximale potentiell generierten Wert

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returns the maximum potentially generated value

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(öffentliche Elementfunktion) [edit]

Non-Member-Funktionen

vergleicht zwei Verteilung Objekte

Original:

compares two distribution objects

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(Funktion) [edit]

Stream führt Eingabe und Ausgabe auf Pseudozufallszahl Verteilung

Original:

performs stream input and output on pseudo-random number distribution

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(Funktion) [edit]

Beispiel

#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
#include <cmath>
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(5,2);

    std::map<int, int> hist;
    for(int n=0; n<10000; ++n) {
        ++hist[std::round(d(gen))];
    }
    for(auto p : hist) {
        std::cout << std::fixed << std::setprecision(1) << std::setw(2)
                  << p.first << ' ' << std::string(p.second/200, '*') << '\n';
    }
}

Output: 

-2 
-1 
 0 
 1 *
 2 ***
 3 ******
 4 ********
 5 **********
 6 ********
 7 *****
 8 ***
 9 *
10 
11 
12

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