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std::piecewise_linear_distribution

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C++
 
Numerics библиотеки
 
Псевдослучайных чисел поколения
Двигатели и адаптеры
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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)
Генераторы
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Generators
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random_device(C++11)
Распределения
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Distributions
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Равномерное распределение
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Uniform distributions
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uniform_int_distribution(C++11)
uniform_real_distribution(C++11)
generate_canonical(C++11)
Бернулли распределения
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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)
Распределения Пуассона
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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)
Нормальное распределение
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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)
Выборка распределения
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Sampling distributions
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discrete_distribution(C++11)
piecewise_constant_distribution(C++11)
piecewise_linear_distribution(C++11)
Семенной последовательности
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Seed Sequences
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C библиотеки
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C library
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rand
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RAND_MAX
 
std::piecewise_linear_distribution
Член функций
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Member functions
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piecewise_linear_distribution::piecewise_linear_distribution
piecewise_linear_distribution::reset
Поколение
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Generation
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piecewise_linear_distribution::operator()
Характеристики
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Characteristics
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piecewise_linear_distribution::param
piecewise_linear_distribution::min
piecewise_linear_distribution::max
Не являющиеся членами функций
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Non-member functions
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operator==
operator!=
operator<<
operator>>
 
Заголовочный файл <random>
template< class RealType = double >
class piecewise_linear_distribution;
 (начиная с C++11)

std::piecewise_linear_distribution produces random floating-point numbers, which are distributed according to a linear probability density function within each of the several subintervals [b
i, b
i+1). The distribution is such that the probability density at each interval boundary is exactly the predefined value p
i.

The probability density for any b
i≤x<b
i+1 is p
i
b
i+1-x
b
i+1-b
i
+ p
i+1
x-b
i
b
i+1-b
i
, where probability densities at interval boundaries p
k are calculated as w
k/S where S is the sum of all None
1
2
(w
k+w
k+1)(b
k+1−b
k).

The set of interval boundaries b
i and the set of weights at boundaries w
i are the parameters of this distribution.

Содержание

[править] Член типов

Член типа
Original:
Member type
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 Definition
result_type RealType
param_type
Тип набора параметров, не указано
Original:
the type of the parameter set, unspecified
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[править] Член функций
строит новые распределения
Original:
constructs new distribution
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(public функция-член) [edit]
Восстанавливает внутреннее состояние распределения
Original:
resets the internal state of the distribution
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(public функция-член) [edit]
Поколение
Original:
Generation
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создает следующее случайное число в распределении
Original:
generates the next random number in the distribution
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(public функция-член) [edit]
Характеристики
Original:
Characteristics
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получает список границ интервала
Original:
obtains the list of interval boundaries
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(public функция-член) [edit]
получает список плотности вероятности в интервале границ
Original:
obtains the list of probability densities at interval boundaries
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(public функция-член) [edit]
получает или задает объект распределения параметра
Original:
gets or sets the distribution parameter object
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(public функция-член) [edit]
возвращает минимальное потенциально сгенерированное значение
Original:
returns the minimum potentially generated value
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(public функция-член) [edit]
возвращает максимальное потенциально сгенерированное значение
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returns the maximum potentially generated value
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(public функция-член) [edit]

[править] Не являющиеся членами функций
сравнивает два объекта распределения
Original:
compares two distribution objects
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(функция) [edit]
осуществляет входной поток и выход на псевдослучайных чисел распределения
Original:
performs stream input and output on pseudo-random number distribution
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(функция) [edit]

[править] Пример

#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
 
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
    // increase the probability from 0 to 5
    // remain flat from 5 to 10
    // decrease from 10 to 15 at the same rate
    std::vector<double> i{0, 5, 10, 15};
    std::vector<double> w{0, 1,   1, 0};
    std::piecewise_linear_distribution<> d(i.begin(), i.end(), w.begin());
 
    std::map<int, int> hist;
    for(int n=0; n<10000; ++n) {
        ++hist[d(gen)];
    }
    for(auto p : hist) {
        std::cout << std::setw(2) << p.first << ' ' << std::string(p.second/100,
    }
}

Вывод: 

0 *
 1 ***
 2 ****
 3 ******
 4 *********
 5 *********
 6 *********
 7 **********
 8 *********
 9 **********
10 *********
11 *******
12 ****
13 ***
14 *
Источник — «http://ru.cppreference.com/mwiki/index.php?title=cpp/numeric/random/piecewise_linear_distribution&oldid=28641»