i want to find determinant of 4x4 matrix in c# please help urgent

    int ss = 4; int count = 0;
    int[,] matrix=new int[ss,ss];
    ArrayList al = new ArrayList() {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 };
    for (int i = 0; i < ss; i++)
    {
        for (int j = 0; j < ss; j++)
        {
            matrix[i, j] =Convert.ToInt32( al[count]);
            ++count;
            Response.Write(matrix[i, j] + " ");
        }
        Response.Write("<br/>");
    }