matrix.c

/* matrix.c — Matrix multiplication demo for Pactor64 */

#include "libc.h"

#define N 4

static void print_matrix(const char *name, int m[N][N]) {

    printf("  %s:\n", name);

    for (int i = 0; i < N; i++) {

        printf("    [");

        for (int j = 0; j < N; j++) {

            printf("%4d", m[i][j]);

            if (j < N - 1) printf(",");

        }

        printf("]\n");

    }

}

int main(int argc, char **argv) {

    printf("=== Matrix Multiplication (%dx%d) ===\n\n", N, N);

    int A[N][N], B[N][N], C[N][N];

    /* Initialize matrices */

    for (int i = 0; i < N; i++)

        for (int j = 0; j < N; j++) {

            A[i][j] = i * N + j + 1;

            B[i][j] = (i == j) ? 1 : 0;  /* Identity matrix */

        }

    print_matrix("Matrix A", A);

    printf("\n");

    print_matrix("Identity B", B);

    /* Multiply A * B (should give A back) */

    for (int i = 0; i < N; i++)

        for (int j = 0; j < N; j++) {

            C[i][j] = 0;

            for (int k = 0; k < N; k++)

                C[i][j] += A[i][k] * B[k][j];

        }

    printf("\n");

    print_matrix("A * B = ", C);

    /* Now multiply A * A */

    for (int i = 0; i < N; i++)

        for (int j = 0; j < N; j++) {

            C[i][j] = 0;

            for (int k = 0; k < N; k++)

                C[i][j] += A[i][k] * A[k][j];

        }

    printf("\n");

    print_matrix("A * A = ", C);

    printf("\nDone!\n");

    return 0;

}