The "Data structure" symmetric matrix and the compressed storage of symmetric matrices

Symmetric matrices:

Set a n*n square a,a any element aij, when and only if AIJ = = Aji (0 <= i <= N-1 && 0 <= J <= N-1), then matrix A is a symmetric matrix. Separated by the diagonal of the matrix, it is divided into upper and lower triangles.

such as the following matrix:

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The relationship between a symmetric matrix and a compression matrix is:

Symmetric matrix symmetricmatrix[i][j] = compression Matrix Array (i* (i+1)/2+j).

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The code is as follows:

#include <iostream>using namespace std;template<class t>class symmtrixmatrix{ Public:    symmtrixmatrix (t* a, size_t size)          :_a (new t[size* (size+1)/2])         , _size (size* (size + 1)  / 2)     {         for  (int i = 0; i < size; i++)          {            for  (int  j = 0; j < size; j++)              {                 if  (I&NBSP;&GT;=&NBSP;J)                 &nbsP {                     //Converting a symmetric matrix to a compression matrix                      _a[i* (i + 1)  / 2+j] = a[i*size+j];                 }                              }        }     }//compression matrix access print     void print (size_t size)     {         for  (int i = 0; i < size;  i++)         {             for&nbsp (int j = 0; j < size; j++)              {                 int row = i;                 int col = j;                 if  (Row < col)                  {                     swap (Row, col);                 }                 cout << _a [Row* (row + 1)/2&Nbsp;+ col] <<  " ";                         }             cout << endl;         }        cout << endl;     }private:    T* _a;    size_t _size;     //is n, symmetric matrix is square};void test () {    int a[5][5] = {                      {  0, 1, 2, 3, 4 },                     { 1, 0, 1, 2, 3 },                      { 2,  1, 0, 1, 2 },                     { 3, 2, 1, 0, 1 },                      { 4, 3, 2, 1, 0 },                    };    symmtrixmatrix<int &GT;&NBSP;SM ((int*) a, 5);     sm. Print (5);     }int main () {    test ();     System ("pause");     return 0;}

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The "Data structure" symmetric matrix and the compressed storage of symmetric matrices