Compression storage of symmetric matrices and 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.

Compressed storage is called a matrix storage only need to store the upper triangle/lower triangle of data, so the maximum storage N (n+1)/2 data.

symmetric matrix and compressed storage correspondence: Lower triangle storage i>=j, Symmetricmatrix[i][j] = = array[i* (i+1)/2+j]

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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

Symmetry.h in template < class t>class symmetry{public://constructor symmetry (T* arr,  size_t size): _arr (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 >= j) {_arr[i* (i + 1)  / 2 +  j] = arr[i*size + j];//compress the symmetric matrix}}}}//print Void print (size_t size) {for  ( int i = 0; i < size; i++) {for  (int j = 0; j  < size; j++) {int row = i;int col = j;if  (row <  col) {swap (row, col);} cout << _arr[row* (row+ 1)  / 2 + col] <<  " ";} Cout << endl;} Cout << endl;} protected:t *_arr;size_t _size;}; In Test.cpp#include  <iostream>using namespace std; #include   "Symmetry.h" void test () {int  arr[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}}; Symmetry<int>s ((int*) arr, 5); S.print (5);} Int main () {Test (); System ("pause"); return 0;}

Compression storage of symmetric matrices and symmetric matrices