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std::inner_product

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< cpp‎ | algorithm

 
 
Biblioteca de algoritmos
Políticas de ejecución (C++17)
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(C++11)(C++11)(C++11)
(C++17)
Operaciones modificadoras de secuencia
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(C++11)
Operaciones de búsqueda binaria
Operaciones de set (en rangos ordenados)
Operaciones de pila
(C++11)
Operaciones minimo/maximo
(C++11)
(C++17)
Permutaciones
Operaciones numéricas
(C++11)
inner_product
Bibliotecas C
 
Definido en la cabecera <numeric>
template< class InputIt1, class InputIt2, class T >

T inner_product( InputIt1 first1, InputIt1 last1,

                 InputIt2 first2, T value );
(1)
template<

    class InputIt1,
    class InputIt2,
    class T,
    class BinaryOperation1,
    class BinaryOperation2
> T inner_product( InputIt1 first1, InputIt1 last1,
                   InputIt2 first2, T value,
                   BinaryOperation1 op1,

                   BinaryOperation2 op2 );
(2)
Calcula producto interior (es decir, la suma de los productos) de la [first1, last1) amplia gama y un nuevo comienzo en first2. La primera versión utiliza para calcular operator* producto de los pares de elementos y operator+ para resumir los productos, la segunda versión utiliza op2 y op1 para estas tareas, respectivamente .
Original:
Computes inner product (i.e. sum of products) of the range [first1, last1) and another range beginning at first2. The first version uses operator* to compute product of the element pairs and operator+ to sum up the products, the second version uses op2 and op1 for these tasks respectively.
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Contenido

[editar] Parámetros

first1, last1 -
la primera gama de elementos
Original:
the first range of elements
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first2 -
el comienzo de la segunda gama de elementos
Original:
the beginning of the second range of elements
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value -
valor inicial de la suma de los productos
Original:
initial value of the sum of the products
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op1 - binary operation function object that will be applied.
Esta función toma un valor devuelto por op2 y el valor actual del acumulador y produce un nuevo valor que se almacena en el acumulador .
Original:
This function takes a value returned by op2 and the current value of the accumulator and produces a new value to be stored in the accumulator.
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The signature of the function should be equivalent to the following:

 Ret fun(const Type1 &a, const Type2 &b);

The signature does not need to have const &.
The types Type1 and Type2 must be such that objects of types T and Type3 can be implicitly converted to Type1 and Type2 respectively. The type Ret must be such that an object of type T can be assigned a value of type Ret. ​

op2 - binary operation function object that will be applied.
Esta función toma un valor de cada gama y produce un nuevo valor .
Original:
This function takes one value from each range and produces a new value.
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The signature of the function should be equivalent to the following:

 Ret fun(const Type1 &a, const Type2 &b);

The signature does not need to have const &.
The types Type1 and Type2 must be such that objects of types InputIt1 and InputIt2 can be dereferenced and then implicitly converted to Type1 and Type2 respectively. The type Ret must be such that an object of type Type3 can be assigned a value of type Ret. ​

Requerimientos de tipo
-
InputIt1, InputIt2 debe reunir los requerimientos de InputIterator.
-
T debe reunir los requerimientos de CopyAssignable y CopyConstructible.

[editar] Valor de retorno

El producto interno de dos rangos .
Original:
The inner product of two ranges.
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[editar] Posible implementación

Primera versión
template<class InputIt1, class InputIt2, class T>
T inner_product(InputIt1 first1, InputIt1 last1,
                InputIt2 first2, T value)
{
    while (first1 != last1) {
         value = value + *first1 * *first2;
         ++first1;
         ++first2;
    }
    return value;
}
Segunda versión
template<class InputIt1, class InputIt2,
         class T,
         class BinaryOperation1, class BinaryOperation2>
T inner_product(InputIt1 first1, InputIt1 last1,
                InputIt2 first2, T value,
                BinaryOperation1 op1
                BinaryOperation2 op2)
{
    while (first1 != last1) {
         value = op1(value, op2(*first1, *first2));
         ++first1;
         ++first2;
    }
    return value;
}

[editar] Ejemplo

#include <numeric>
#include <iostream>
#include <vector>
#include <functional>
int main()
{
    std::vector<int> a{0, 1, 2, 3, 4};
    std::vector<int> b{5, 4, 2, 3, 1};
 
    int r1 = std::inner_product(a.begin(), a.end(), b.begin(), 0);
    std::cout << "Inner product of a and b: " << r1 << '\n';
 
    int r2 = std::inner_product(a.begin(), a.end(), b.begin(), 0,
                                std::plus<int>(), std::equal_to<int>());
    std::cout << "Number of pairwise matches between a and b: " <<  r2 << '\n';
}

Salida:

Inner product of a and b: 21
Number of pairwise matches between a and b: 2

[editar] Ver también

resume una serie de elementos
Original:
sums up a range of elements
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(plantilla de función) [editar]
calcula la suma parcial de una serie de elementos
Original:
computes the partial sum of a range of elements
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(plantilla de función) [editar]