inner_product
计算两个范围元素产品的总和并将其添加到指定的初始值或计算求和与产品二进制操作由其他指定的二元运算一个通用程序的结果。
template<class InputIterator1, class InputIterator2, class Type>
Type inner_product(
InputIterator1 _First1,
InputIterator1 _Last1,
InputIterator2 _First2,
Type _Val
);
template<class InputIterator1, class InputIterator2, class Type,
class BinaryOperation1, class BinaryOperation2>
Type inner_product(
InputIterator1 _First1,
InputIterator1 _Last1,
InputIterator2 _First2,
Type _Val,
BinaryOperation1 _Binary_op1,
BinaryOperation2 _Binary_op2
);
参数
_First1
解决输入的迭代器在内积或通用内积与第二个范围是要计算的第一个范围的第一个元素。_Last1
解决输入的迭代器在内积或通用内积与第二个范围是要计算的第一个范围的最后一个元素。_First2
解决输入的迭代器在内积或通用内积与第一个范围是要计算的第二个范围的第一个元素。_Val
内积或通用内积在范围之内要添加的初始值。_Binary_op1
替换总和的内积操作的二进制操作应用于内积的泛化的元素产品。_Binary_op2
替换内积元素操作的二进制操作内积的泛化乘以。
返回值
第一个成员函数返回元素产品的总和并向该属性所指定的初始值。 因此对于值 ai和 二进制文件的大小，它返回:
_Val + ( a1 * b1 ) + ( a2 * b2 ) +
通过迭代替换 _Val 用 _Val + (*ai * *bi )。
第二个成员函数返回:
_Val _Binary_op1 ( a1 _Binary_op2b1 ) _Binary_op1 ( a2 _Binary_op2b2 ) _Binary_op1
通过迭代替换 _Val 用 _Val _Binary_op1 (*a我 _Binary_op2 *b)我。
备注
初始值确保将具有一个定义完善的结果，当范围为空时，在 _Val 返回情况下。 二元运算不需要关联或可交换的。 该范围必须是有效的，并且复杂是线性与该范围。 该二元运算符的返回类型必须是转换为 *** 类型 *** 在迭代期间确保关闭。
示例
// numeric_inner_prod.cpp
// compile with: /EHsc
#include <vector>
#include <list>
#include <numeric>
#include <functional>
#include <iostream>
int main()
{
using namespace std;
vector <int> v1, v2(7), v3(7);
vector <int>::iterator iter1, iter2, iter3;
int i;
for (i = 1; i <= 7; i++)
{
v1.push_back(i);
}
cout << "The original vector v1 is:\n ( " ;
for (iter1 = v1.begin(); iter1 != v1.end(); iter1++)
cout << *iter1 << " ";
cout << ")." << endl;
list <int> l1, l2(7);
list <int>::iterator lIter1, lIter2;
int t;
for (t = 1; t <= 7; t++)
{
l1.push_back(t);
}
cout << "The original list l1 is:\n ( " ;
for (lIter1 = l1.begin(); lIter1 != l1.end(); lIter1++)
cout << *lIter1 << " ";
cout << ")." << endl;
// The first member function for the inner product
int inprod;
inprod = inner_product(v1.begin(), v1.end(), l1.begin(), 0);
cout << "The inner_product of the vector v1 and the list l1 is: "
<< inprod << "." << endl;
// Constructing a vector of partial inner_products between v1 & l1
int j = 0, parinprod;
for (iter1 = v1.begin(); iter1 != v1.end(); iter1++) {
parinprod = inner_product(v1.begin(), iter1 + 1, l1.begin(), 0);
v2[j] = parinprod;
j++;
}
cout << "Vector of partial inner_products between v1 & l1 is:\n ( " ;
for (iter2 = v2.begin(); iter2 != v2.end(); iter2++)
cout << *iter2 << " ";
cout << ")." << endl << endl;
// The second member function used to compute
// the product of the element-wise sums
int inprod2;
inprod2 = inner_product (v1.begin(), v1.end(),
l1.begin(), 1, multiplies<int>(), plus<int>());
cout << "The sum of the element-wise products of v1 and l1 is: "
<< inprod2 << "." << endl;
// Constructing a vector of partial sums of element-wise products
int k = 0, parinprod2;
for (iter1 = v1.begin(); iter1 != v1.end(); iter1++)
{
parinprod2 =
inner_product(v1.begin(), iter1 + 1, l1.begin(), 1,
multiplies<int>(), plus<int>());
v3[k] = parinprod2;
k++;
}
cout << "Vector of partial sums of element-wise products is:\n ( " ;
for (iter3 = v3.begin(); iter3 != v3.end(); iter3++)
cout << *iter3 << " ";
cout << ")." << endl << endl;
}
Output
The original vector v1 is:
( 1 2 3 4 5 6 7 ).
The original list l1 is:
( 1 2 3 4 5 6 7 ).
The inner_product of the vector v1 and the list l1 is: 140.
Vector of partial inner_products between v1 & l1 is:
( 1 5 14 30 55 91 140 ).
The sum of the element-wise products of v1 and l1 is: 645120.
Vector of partial sums of element-wise products is:
( 2 8 48 384 3840 46080 645120 ).
要求
标头: <numeric>
命名空间: std