std::exponential_distribution
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| Déclaré dans l'en-tête <random>
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| template< class RealType = double > class exponential_distribution; |
(depuis C++11) | |
Produit aléatoires non négatives valeurs à virgule flottante x, répartis selon la fonction de densité de probabilité:
Original:
Produces random non-negative floating-point values x, distributed according to probability density function:
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- P(x|λ) = λe-λx
La valeur obtenue n'est pas le temps / distance jusqu'au prochain événement aléatoire si des événements aléatoires se produisent à vitesse constante λ par unité de temps / distance. Par exemple, cette distribution décrit le temps entre les clics d'un compteur Geiger ou la distance entre des mutations ponctuelles dans un brin d'ADN .
Original:
The value obtained is the time/distance until the next random event if random events occur at constant rate λ per unit of time/distance. For example, this distribution describes the time between the clicks of a Geiger counter or the distance between point mutations in a DNA strand.
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C'est la contrepartie continue de std::geometric_distribution
Original:
This is the continuous counterpart of std::geometric_distribution
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[modifier] Types de membres
| Type du membre | Définition |
result_type
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RealType |
param_type
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le type du jeu de paramètres, sans précision
Original: the type of the parameter set, unspecified The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
[modifier] Fonctions membres
| construit distribution Original: constructs new distribution The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique) | |
| réinitialise l'état interne de la distribution Original: resets the internal state of the distribution The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique) | |
Original: Generation The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. | |
| génère le nombre aléatoire suivant dans la distribution Original: generates the next random number in the distribution The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique) | |
Original: Characteristics The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. | |
| renvoie le paramètre lambda de distribution (taux d'événements) Original: returns the lambda distribution parameter (rate of events) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique) | |
| obtient ou définit l'objet de paramètre de distribution Original: gets or sets the distribution parameter object The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique) | |
| renvoie la valeur minimale potentiellement générées Original: returns the minimum potentially generated value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique) | |
| renvoie la valeur maximale potentiellement générées Original: returns the maximum potentially generated value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique) | |
[modifier] Fonctions annexes
| compare deux objets de distribution Original: compares two distribution objects The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) | |
| effectue flux d'entrée et de sortie sur la distribution de nombre pseudo-aléatoire Original: performs stream input and output on pseudo-random number distribution The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) | |
[modifier] Exemple
#include <iostream> #include <iomanip> #include <string> #include <map> #include <random> int main() { std::random_device rd; std::mt19937 gen(rd()); // if particles decay once per second on average, // how much time, in seconds, until the next one? std::exponential_distribution<> d(1); std::map<int, int> hist; for(int n=0; n<10000; ++n) { ++hist[2*d(gen)]; } for(auto p : hist) { std::cout << std::fixed << std::setprecision(1) << p.first/2.0 << '-' << (p.first+1)/2.0 << ' ' << std::string(p.second/200, '*') << '\n'; }
Résultat :
0.0-0.5 ******************* 0.5-1.0 *********** 1.0-1.5 ******* 1.5-2.0 **** 2.0-2.5 ** 2.5-3.0 * 3.0-3.5 3.5-4.0
[modifier] Liens externes
Weisstein, Eric W. "Exponential Distribution." De MathWorld - Une ressource Web Wolfram .
Original:
Weisstein, Eric W. "Exponential Distribution." From MathWorld--A Wolfram Web Resource.
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