# 2-D Arrays (Matrices)

• 11-27-2003
Mak
2-D Arrays (Matrices)
I'm confused :confused:

I have to creat 2 matrices and then produce a third matrxi. But here is the problem that i have:

Question states "third matrix whose all off diagonal entries are zero and the diagonal entries are the sum of first 2 matrices."

Off diagonal? diagonal? I dotn get that

1 3 5
5 6 7
7 9 9

would diagonal be 1,6 and 9? and the rest off diagonal?

and then i'm not really sure how to add them...so far i have:

Code:

```void get_mat(int mat[][3]); void get_mat2(int matx[][3]); void add_mat(int mat1[][3], int mat2[][3], int mat3[][3]); void ptr_mat(int mat[][3]); main() { int matrix[3][3]; int matrix1[3][3]; int matrix2[3][3]; get_mat(matrix); get_mat2(matrix1); add_mat(matrix, matrix1, matrix2); ptr_mat(matrix2); } void get_mat(int mat[][3]) { int i, j; for(i=0; i<3; i++){ for(j=0; j<3; j==){ printf("Please enter Matrix 1 [%d][%d]", i,j)' scamf("%d", &mat[i][j]);                 }         } } void get_mat(int mat2[][3]) { int i, j; for(i=0; i<3; i++){ for(j=0; j<3; j==){ printf("Please enter Matrix 1 [%d][%d]", i,j)' scamf("%d", &mat2[i][j]);                 }         } }```

thanks
• 11-27-2003
Salem
> would diagonal be 1,6 and 9? and the rest off diagonal?
Seems about right to me, from what I can remember.

This indexes the diagonal
for ( i = 0 ; i < n ; i++ ) mat[i][i] = 0;
• 11-27-2003
Mak
never mind...got it working