std::slice

 

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通用的數值運算 Original: Generic numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

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std::valarray

成員函數 Original: Member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
valarray::valarray valarray::~valarray valarray::operator= valarray::operator[] valarray::swap valarray::size valarray::resize valarray::sum valarray::min valarray::max valarray::shift valarray::cshift valarray::apply	valarray::operator+ valarray::operator- valarray::operator~ valarray::operator! valarray::operator+= valarray::operator-= valarray::operator*= valarray::operator/= valarray::operator%= valarray::operator&= valarray::operator|= valarray::operator^= valarray::operator<<= valarray::operator>>=
非成員函數 Original: Non-member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
swap （C++11） begin （C++11） end （C++11） abs exp log log10 pow sqrt sin cos tan asin acos atan atan2 sinh cosh tanh	operator* operator/ operator% operator+ operator- operator^ None operator& operator| operator<< operator>> operator&& operator None operator== operator!= operator< operator> operator<= operator>=
Helper類 Original: Helper classes The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
slice_array gslice_array indirect_array	slice gslice mask_array

 

Defined in header <valarray>
class slice;

std::slice是選擇器類，用於標識一個子集，std::valarrayBLAS片。類型std::slice一個目的持有三個值：起始索引，步幅，和中的值的子集的總數。類型std::slice的對象可以被用作索引用的valarray的operator[].

Original:

std::slice is the selector class that identifies a subset of std::valarray similar to BLAS slice. An object of type std::slice holds three values: the starting index, the stride, and the total number of values in the subset. Objects of type std::slice can be used as indexes with valarray's operator[].

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成員函數

(constructor)	構建一個切片 Original: constructs a slice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成員函數）
start	訪問開始的切片 Original: accesses the start of the slice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成員函數）
size	訪問的大小的切片 Original: accesses the size of the slice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成員函數）
stride	訪問步幅的切片 Original: accesses the stride of the slice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成員函數）

為例

准系統的valarray追查計算功能的支持Matrix類.

Original:

Barebones valarray-backed Matrix class with a 追查 calculating function.

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#include <iostream>
#include <valarray>
class Matrix {
    std::valarray<int> data;
    int dim;
 public:
    Matrix(int r, int c) : data(r*c), dim(c) {}
    int& operator()(int r, int c) {return data[r*dim + c];}
    int trace() const {
        return data[std::slice(0, dim, dim+1)].sum();
    }
};
int main()
{
    Matrix m(3,3);
    int n = 0;
    for(int r=0; r<3; ++r)
       for(int c=0; c<3; ++c)
           m(r, c) = ++n;
    std::cout << "Trace of the matrix (1,2,3) (4,5,6) (7,8,9) is " << m.trace() << '\n';
}

Output:

Trace of the matrix (1,2,3) (4,5,6) (7,8,9) is 15

另請參閱

operator[]	獲取/設置valarray的元素，切片，或面罩 Original: get/set valarray element, slice, or mask The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成員函數）
gslice	廣義片的valarray的起始索引，設置的長度，設置的步伐 Original: generalized slice of a valarray: starting index, set of lengths, set of strides The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （類）
slice_array	代理的valarray的應用切片後的一個子集 Original: proxy to a subset of a valarray after applying a slice The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （類模板）