int
main(int argc, char *argv[])
{
int i, j;
int a[4][4] = { {1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16} };
int b[4][4] = { {1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16} };
int n;
int **c;
c = malloc(sizeof(int *) * 4);
for (i = 0; i < 4; i++)
c[i] = malloc(sizeof(int) * 4);
square_matrix_multiply((int *) a, (int *) b, 4, (int *) c);
debug_matrix((int *) c, 4);
return 0;
}
int main() {
//int d[4] = {1, 3, 7, 5};
//int e[4] = {6, 8, 4, 2};
//int f[4];
//int A[16] = {-1, 1, 1, -1, 1, -1, -1, 1, 1, -1, -1, 1, -1, 1, 1, -1};
int A[16] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
int B[16], C[16];
int i, j;
//
//square_matrix_multiply(d, e, f, 2);
//printf("Matrix d:\n");
//for (i = 0; i < 2; i++) {
//for (j = 0; j < 2; j++)
//printf("%d\t", *(d + 2 * i + j));
//printf("\n");
//}
//printf("\n");
//printf("Matrix e:\n");
//for (i = 0; i < 2; i++) {
//for (j = 0; j < 2; j++)
//printf("%d\t", *(e + 2 * i + j));
//printf("\n");
//}
//printf("\n");
//printf("The result of matrix multiply d * e:\n");
//for (i = 0; i < 2; i++) {
//for (j = 0; j < 2; j++)
//printf("%d\t", *(f + 2 * i + j));
//printf("\n");
//}
square_matrix_multiply(A, A, B, 4);
//square_matrix_multiply(A, B, C, 4);
//square_matrix_multiply(C, C, B, 4);
//printf("Matrix A:\n");
//for (i = 0; i < 4; i++) {
//for (j = 0; j < 4; j++)
//printf("%d\t", *(A + 4 * i + j));
//printf("\n");
//}
//printf("\n");
//printf("The result is:\n");
for (i = 0; i < 4; i++) {
for (j = 0; j < 4; j++)
printf("%d\t", *(B + 4 * i + j));
printf("\n");
}
return 0;
}
void square_matrix_multiply(int *a1, int *b1, int num, int *c)
{
int n = num, i, j;
int *a11, *a12, *a21, *a22;
int *b11, *b12, *b21, *b22;
int *c11, *c12, *c21, *c22;
int *c11a, *c11b, *c12a, *c12b, *c21a, *c21b, *c22a, *c22b;
if (n == 1)
*c = *a1 * *b1;
else {
a11 = malloc(sizeof(int) * num * num / 4);
a12 = malloc(sizeof(int) * num * num / 4);
a21 = malloc(sizeof(int) * num * num / 4);
a22 = malloc(sizeof(int) * num * num / 4);
b11 = malloc(sizeof(int) * num * num / 4);
b12 = malloc(sizeof(int) * num * num / 4);
b21 = malloc(sizeof(int) * num * num / 4);
b22 = malloc(sizeof(int) * num * num / 4);
for (i = 0; i < num; i++) {
for (j = 0; j < num; j++)
{
if (i + 1 <= num / 2 && j + 1 <= num / 2)
{
*(a11 + i * num / 2 + j) = *(a1 + i * num + j);
*(b11 + i * num / 2 + j) = *(b1 + i * num + j);
}
if (i + 1 <= num / 2 && j + 1 > num / 2)
{
*(a12 + i * num / 2+ (j - num/2)) = *(a1 + i * num + j);
*(b12 + i * num / 2+ (j - num/2)) = *(b1 + i * num + j);
}
if (i + 1 > num / 2 && j + 1 <= num / 2)
{
*(a21 + (i - num / 2) * num / 2 + j) = *(a1 + i * num + j);
*(b21 + (i - num / 2) * num / 2 + j) = *(b1 + i * num + j);
}
if (i + 1 > num / 2 && j + 1 > num / 2)
{
*(a22 + (i - num / 2) * num / 2 + (j - num / 2)) = *(a1 + i * num + j);
*(b22 + (i - num / 2) * num / 2 + (j - num / 2)) = *(b1 + i * num + j);
}
}
}
c11a = malloc(sizeof(int) * (num / 2) * (num / 2));
c11b = malloc(sizeof(int) * (num / 2) * (num / 2));
c11 = malloc(sizeof(int) * (num / 2) * (num / 2));
//computation C11
square_matrix_multiply(a11, b11, num / 2, c11a);
square_matrix_multiply(a12, b21, num / 2, c11b);
square_matrix_add(c11a, c11b, c11, num / 2);
c12a = malloc(sizeof(int) * (num / 2) * (num / 2));
c12b = malloc(sizeof(int) * (num / 2) * (num / 2));
c12 = malloc(sizeof(int) * (num / 2) * (num / 2));
//computation C12
square_matrix_multiply(a11, b12, num / 2, c12a);
square_matrix_multiply(a12, b22, num / 2, c12b);
square_matrix_add(c12a, c12b, c12, num / 2);
c21a = malloc(sizeof(int) * (num / 2) * (num / 2));
c21b = malloc(sizeof(int) * (num / 2) * (num / 2));
c21 = malloc(sizeof(int) * (num / 2) * (num / 2));
//computation C21
square_matrix_multiply(a21, b11, num / 2, c21a);
square_matrix_multiply(a22, b21, num / 2, c21b);
square_matrix_add(c21a, c21b, c21, num / 2);
c22a = malloc(sizeof(int) * (num / 2) * (num / 2));
c22b = malloc(sizeof(int) * (num / 2) * (num / 2));
c22 = malloc(sizeof(int) * (num / 2) * (num / 2));
//computation C22
square_matrix_multiply(a21, b12, num / 2, c22a);
square_matrix_multiply(a22, b22, num / 2, c22b);
square_matrix_add(c22a, c22b, c22, num / 2);
for (i = 0; i < num; i++)
for (j = 0; j < num; j++)
{
if (i + 1 <= num / 2 && j + 1 <= num / 2) *(c + i * num + j) = *(c11 + i * num / 2 + j);
if (i + 1 <= num / 2 && j + 1 > num / 2) *(c + i * num + j) = *(c12 + i * num / 2 + (j - num / 2));
if (i + 1 > num / 2 && j + 1 <= num / 2) *(c + i * num + j) = *(c21 + (i - num/2) * num / 2 + j);
if (i + 1 > num / 2 && j + 1 > num / 2) *(c + i * num + j) = *(c22 + (i - num/2) * num / 2 + (j - num/2));
}
}
}
