Varianti

    std::poisson_distribution

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    <metanoindex/>

     
    C++
     
    Numeri libreria
    Comuni funzioni matematiche
    Virgola mobile ambiente
    I numeri complessi
    Array numerici
    Pseudo-casuale generazione
    In fase di compilazione aritmetica razionale (C++11)
    Generici operazioni numeriche
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    Generic numeric operations
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    iota(C++11)
    accumulate
    inner_product
    adjacent_difference
    partial_sum
     
    Pseudo-casuale generazione
    Motori e adattatori del motore
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    Engines and engine adaptors
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    linear_congruential_engine(C++11)
    mersenne_twister_engine(C++11)
    subtract_with_carry_engine(C++11)
    discard_block_engine(C++11)
    independent_bits_engine(C++11)
    shuffle_order_engine(C++11)
    Generatori
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    Generators
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    random_device(C++11)
    Distribuzioni
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    Distributions
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    Distribuzioni uniformi
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    Uniform distributions
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    uniform_int_distribution(C++11)
    uniform_real_distribution(C++11)
    generate_canonical(C++11)
    Bernoulli distribuzioni
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    Bernoulli distributions
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    bernoulli_distribution(C++11)
    binomial_distribution(C++11)
    negative_binomial_distribution(C++11)
    geometric_distribution(C++11)
    Poisson distribuzioni
    Original:
    Poisson distributions
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    poisson_distribution(C++11)
    exponential_distribution(C++11)
    gamma_distribution(C++11)
    weibull_distribution(C++11)
    extreme_value_distribution(C++11)
    Distribuzioni normali
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    Normal distributions
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    normal_distribution(C++11)
    lognormal_distribution(C++11)
    chi_squared_distribution(C++11)
    cauchy_distribution(C++11)
    fisher_f_distribution(C++11)
    student_t_distribution(C++11)
    Distribuzioni di campionamento
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    Sampling distributions
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    discrete_distribution(C++11)
    piecewise_constant_distribution(C++11)
    piecewise_linear_distribution(C++11)
    Seed Sequenze
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    Seed Sequences
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    seed_seq(C++11)
    Libreria C
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    C library
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    rand
    srand
    RAND_MAX
     
    std::poisson_distribution
    Membri funzioni
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    Member functions
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    poisson_distribution::poisson_distribution
    poisson_distribution::reset
    Generazione
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    Generation
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    poisson_distribution::operator()
    Caratteristiche
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    Characteristics
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    poisson_distribution::mean
    poisson_distribution::param
    poisson_distribution::min
    poisson_distribution::max
    Non membri funzioni
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    Non-member functions
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    operator==
    operator!=
    operator<<
    operator>>
     
    <tbody> </tbody>
    Elemento definito nell'header <random>
    template< class IntType = int > class poisson_distribution;
    		 (dal C++11)
    Produce casuale non negativo i valori interi, distribuito in base alla funzione di probabilità discrete:
    Original:
    Produces random non-negative integer values i, distributed according to discrete probability function:
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    P(i|μ) =
    e-μ
    ·μi
    i!

    The value obtained is the probability of exactly i occurrences of a random event if the expected, mean number of its occurrence under the same conditions (on the same time/space interval) is μ.

    Membri tipi

    Membro tipo
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    Member type
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    		 Definition
    result_type IntType
    param_type
    il tipo di set di parametri, non specificato
    Original:
    the type of the parameter set, unspecified
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    Membri funzioni
    costruisce nuova distribuzione
    Original:
    constructs new distribution
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    (metodo pubblico) [modifica]
    ripristina lo stato interno della distribuzione
    Original:
    resets the internal state of the distribution
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    (metodo pubblico) [modifica]
    Generazione
    Original:
    Generation
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    genera il successivo numero casuale nella distribuzione
    Original:
    generates the next random number in the distribution
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    (metodo pubblico) [modifica]
    Caratteristiche
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    Characteristics
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    		 returns the mean distribution parameter (mean number of occurrences of the event)
    (metodo pubblico) [modifica]
    ottiene o imposta l'oggetto parametro di distribuzione
    Original:
    gets or sets the distribution parameter object
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    (metodo pubblico) [modifica]
    restituisce il valore minimo potenzialmente generato
    Original:
    returns the minimum potentially generated value
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    (metodo pubblico) [modifica]
    restituisce il valore massimo potenzialmente generato
    Original:
    returns the maximum potentially generated value
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    (metodo pubblico) [modifica]

    Non membri funzioni
    confronta due oggetti di distribuzione
    Original:
    compares two distribution objects
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    (funzione) [modifica]
    esegue flusso di ingresso e di uscita sul pseudo-casuale distribuzione numerica
    Original:
    performs stream input and output on pseudo-random number distribution
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    (funzione) [modifica]

    Esempio

    #include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());

    // if an event occurs 4 times a minute on average
    // how often is it that it occurs n times in one minute?
    std::poisson_distribution<> d(4);

    std::map<int, int> hist;
    for(int n=0; n<10000; ++n) {
        ++hist[d(gen)];
    }
    for(auto p : hist) {
        std::cout << p.first <<
                ' ' << std::string(p.second/100, '*') << '\n';
    }
}

    Output: 

    0 *
1 *******
2 **************
3 *******************
4 *******************
5 ***************
6 **********
7 *****
8 **
9 *
10 
11 
12 
13

    Collegamenti esterni

    Weisstein, Eric W. "Poisson Distribution." Da MathWorld - Una risorsa Web Wolfram.
    Original:
    Weisstein, Eric W. "Poisson Distribution." From MathWorld--A Wolfram Web Resource.
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