Archive:Matrix multiplication using C

<source lang="c">/* Program to implement matrix multiplication. */ /* Performed by Milan. */ /* Edited by Gergo: resolved some portability issues */

1. include <stdio.h>
2. include <stdlib.h>

int main(void) {

       int a[10][10], b[10][10], c[10][10];
       int i, j, m, n, x, y, k;

       /* Entering values for matrix a...*/
       printf ("\n Enter the rows and columns of a: ");
       scanf ("%d%d", &m, &n);

       for (i = 0; i < m; i++)
       {
               for (j = 0; j < n; j++)
               {
                       printf (" a[%d][%d] = ", (i+1), (j+1));
                       scanf ("%d", &a[i][j]);
               }
               printf ("\n");
       }

       /* Entering values for matrix b... */
       printf ("\n Enter the rows and columns of b: ");
       scanf ("%d%d", &x, &y);

       for (i = 0; i < x; i++)
       {
               for (j = 0; j < y; j++)
               {
                       printf (" b[%d][%d] = ", (i+1), (j+1));
                       scanf ("%d", &b[i][j]);
               }
               printf ("\n");
       }

       /* Calculations */
       if ( n != x)
       {
               printf ("\n Error!! Rows of a don't match with columns of b.");
               printf ("\n Multiplication Impossible.");
               exit(EXIT_FAILURE);
       }
       else
       {
               for (i = 0; i < m; i++)
               {
                       for (j = 0; j < y; j++)
                       {
                               c[i][j] = 0;
                               for (k = 0; k < n; k++)
                               {
                                       c[i][j]+=a[i][k]*b[k][j];
                               }
                       }
               }
       }

       /* Output */
       printf ("\n The resultant c is:\n");
       for (i = 0; i < m; i++)
       {
               for (j = 0; j < y; j++)
               {
                       printf (" c[%d][%d] = %d", (i+1), (j+1), c[i][j]);
               }
               printf ("\n");
       }

       return 0;

} /* Output:

Enter the rows and columns of a: 2 2
a[1][1] = 1
a[1][2] = 2

a[2][1] = 3
a[2][2] = 4

Enter the rows and columns of b: 2 2
b[1][1] = 2
b[1][2] = 1

b[2][1] = 2
b[2][2] = 2

The resultant c is:
c[1][1] = 6 c[1][2] = 5
c[2][1] = 14 c[2][2] = 11

• /

</source>