matrix.c

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

typedef struct matrix 
{
    size_t size;
    int**  values;
} matrix_t;

matrix_t make_matrix(double n, int lim, double p)
{
    size_t n_rows = lim - 1;
    int** result = malloc(n_rows * sizeof(int*));

    if (result == NULL)
        exit(1);

    int max = 0;
    int i = 0;
    do
    {
        result[i] = malloc(3 * sizeof(int));

        for (int j = 0; j < 3; j++)
        {
            max = j + i;
            result[i][j] = pow(n + max, p);
        }

        i += 1;
    }
    while (i <= lim && max < lim);

    matrix_t m;
    m.size = n_rows;
    m.values = result;

    return m;
}

void print_matrix(matrix_t* m)
{
    for (int i = 0; i < m->size; i++)
    {
        for (int j = 0; j < 3; j++)
        {
            printf("%d ", m->values[i][j]);
        }
        printf("\n");
    }
}

matrix_t multiply_matrix(matrix_t* a, matrix_t* b)
{
    int** result = malloc(a->size * sizeof(int*));
    for (int i = 0; i < a->size; i++)
    {
        result [i] = malloc(3 * sizeof(int*));

        for (int j = 0; j < 3; j++)
        {
            for (int k = 0; k < 3; k++)
            {
                result[i][j] += a->values[i][k] * b->values[k][j];
            }
        }
    }

    matrix_t m;
    m.size = a->size;
    m.values = result;

    return m;
}

int main()
{
    int n;
    scanf("%d", &n);

    matrix_t a = make_matrix(n, 3, 2);
    matrix_t b = make_matrix(n, 4, 3);

    matrix_t m = multiply_matrix(&a, &b);
    print_matrix(&m);
}