# The realization of the two N*N matrix multiplication, matrix is represented by a

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The realization of the two N*N matrix multiplication, matrix is represented by a one-dimensional array.

```1     void Add(int rows, int cols)
2     {
3        for(int i= 0;i<rows;i++)
4        {
5        for(int j=0;j<cols;j++)
6           result[i][j]=mat1[i][j]+mat2[i][j];
7        }
8     } ```

If the two matrix to do multiplication: only in the number of columns in a matrix of rows and the other a matrix of the same , can do two matrix multiplication.

How to get the matrix transpose:

The transpose of the matrix is a matrix, change in the original matrix transpose matrix column for. For example, the following a 3× 3 matrix;:

1 2 3

6 7 8

4 5 9

Then the transpose it into:

1 6 4

2 7 5

3 8 9

Let us from the programmer's point of view carefully examine this phenomenon. Assuming that the original array is M, transposed matrix is MT. Then M[1][0] = 6, we found that MT in the transposed matrix [0][1] = 6. Therefore, we can get the conclusion: program to transpose a matrix is actually on the index variable. Technical terms:

1. MT[Row][Column] = M[Column][Row];

The following is the transpose of C code:

[cpp] view plaincopy

1. void show_transpose(float mat[][10],int row,int col)

2. {

3. int i,j;

4. for(i=0;i<row;i++)

5. {

6. for(j=0;j<col;j++)

7. printf("%f\t",mat[j][i]);

8. printf("\n");

9. }

10. }

This method shows the matrix transpose.

[cpp] view plaincopy

1. #include<iostream>
2. using namespace std;
3. #define size 2
4.
5. int multi(int *a , int *b , int N)
6. {
7. int i , j , k , temp;

8. int *c = (int*)malloc(N * N * sizeof(int));

9.
10. for(i = 0 ; i < N ; i++)

11. {

12. for(j = 0 ; j < N ; j++)

13. {

14. temp = i * N + j;

15. *(c + temp) = 0;

16. for(k = 0 ; k < N ; k++)

17. {

18. *(c + temp) += a[i * N + k] * b[k * N + j];

19. }

20. cout<<*(c + temp)<<" ";

21. }

22. }

23. return *c;

24. }
25.
26. int main()
27. {
28. int a[size * size] = {2 , 1 , 4 , 3};

29. int b[size * size] = {1 , -1 , 3 , 2};

30. multi(a , b , size);

31.
32. return 0;

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Posted by Hunter at November 16, 2013 - 2:08 PM