## Tuesday 22 January 2013

### Matrix Multiplication Using DMA [C Source Code]

This post provides a source code for matrix multiplication by dynamically allocating memory for matrices to be multiplied and multiplication of those matrices.

```#include <stdio.h>
#include <stdlib.h>

int main()
{
int **A, **B, **C, m, n, p, q, i, j, k;
printf("Enter the size of matrix A: ");
scanf("%d %d", &m, &n);

printf("Enter the size of matrix B: ");
scanf("%d %d", &p, &q);

if (n == p)
{
A = malloc(m * sizeof(int));
B = malloc(p * sizeof(int));
C = malloc(m * sizeof(int));

for (i = 0; i < m; i++)
{
A[i] = malloc(n * sizeof(int));
C[i] = malloc(q * sizeof(int));
}

for (i = 0; i < p; i++)
{
B[i] = malloc(q * sizeof(int));
}

printf("Enter the matrix A:\n\n");
for (i = 0; i < m; i++)
{
for (j = 0; j < n; j++)
{
scanf("%d", &A[i][j]);
}
}

printf("Enter the matrix B:\n\n");
for (i = 0; i < p; i++)
{
for (j = 0; j < q; j++)
{
scanf("%d", &B[i][j]);
}
}

for (i = 0; i < m; i++)
{
for (j = 0; j < q; j++)
{
C[i][j] = 0;
for (k = 0; k < n; k++)
{
C[i][j] = C[i][j] + (A[i][k] * B[k][j]);
}
}
}

printf("Multiplication of given matrices is: \n\n");

for (i = 0; i < m; i++)
{
for (j = 0; j < q; j++)
{
printf("%d ", C[i][j]);
}
printf("\n");
}

for (i = 0; i < m; i++)
{
free(A[i]);
free(C[i]);
}
for (i = 0; i < p; i++)
{
free(B[i]);
}
free(A);
free(B);
free(C);
}
else
{
printf("Matrix multiplication is not possible for given size\n\n");
}
return 0;
}
```
```samar@samar-Techgaun:~\$ gcc -Wall -o matrix_mul matrix_mul.c
samar@samar-Techgaun:~\$ ./matrix_mul
Enter the size of matrix A: 3 2
Enter the size of matrix B: 2 3
Enter the matrix A:

1 2
3 4
5 6
Enter the matrix B:

1 2 3
4 5 6
Multiplication of given matrices is:

9 12 15
19 26 33
29 40 51
```