C Program to multiply two matrices

C Program to multiply two matrices

The below program multiplies two square matrices of size 4*4, we can change N for different dimension.

// C program to multiply two square matrices.

#include <stdio.h>

#define N 4

// This function multiplies mat1[][] and mat2[][],

// and stores the result in res[][]

void multiply(int mat1[][N], int mat2[][N], int res[][N])

{

    int i, j, k;

    for (i = 0; i < N; i++)

    {

        for (j = 0; j < N; j++)

        {

            res[i][j] = 0;

            for (k = 0; k < N; k++)

                res[i][j] += mat1[i][k]*mat2[k][j];

        }

    }

}

int main()

{

    int mat1[N][N] = { {1, 1, 1, 1},

                    {2, 2, 2, 2},

                    {3, 3, 3, 3},

                    {4, 4, 4, 4}};

    int mat2[N][N] = { {1, 1, 1, 1},

                    {2, 2, 2, 2},

                    {3, 3, 3, 3},

                    {4, 4, 4, 4}};

    int res[N][N]; // To store result

    int i, j;

    multiply(mat1, mat2, res);

    printf("Result matrix is \n");

    for (i = 0; i < N; i++)

    {

        for (j = 0; j < N; j++)

           printf("%d ", res[i][j]);

        printf("\n");

    }

    return 0;

}

Output:

Result matrix is

10 10 10 10

20 20 20 20

30 30 30 30

40 40 40 40

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