Minor of a determinant

This is what I have for finding the minor. I think I could make it more condense to run faster but don't know what to do really. My program works with this function, but I'm just wondering what I can do to make it run smoother.

Code:

double minor(double A[][4], int i, int j)
{
	double find_minor[3][3];
	int counta = 0;
	int countb = 0;

	for (int x = 0; x < 4; x++)
	{
		if (x != j)
		{
			for (int y = 0; y < 4; y++)
			{
				if (y != i)
				{
					find_minor[counta][countb] = A[x][y];
					++countb;
					if (countb % 3 == 0)
					{
						countb = 0;
					}
				}
			}
			++counta;
		}
	}
	double minordet = find_minor[0][0]*(find_minor[1][1]*find_minor[2][2]-find_minor[2][1]*find_minor[1][2]) -
		find_minor[0][1]*(find_minor[1][0]*find_minor[2][2]-find_minor[2][0]*find_minor[1][2])+find_minor[0][2] *
		(find_minor[1][0]*find_minor[2][1]-find_minor[2][0]*find_minor[1][1]);
	
	return minordet;
}

I don't know about the speed, but you should iniitlaize find_minor just to make sure no elements contain random data after that loop ends.

Code:

double find_minor[3][3] = {0};

loop counters should be from 0 to 3, not 0 to 4

Code:

for (int x = 0; x < 3; x++)
and
for (int y = 0; y < 3; y++)