def c_fd2(matrix, x, y):
    """
    Second Central difference of a given x and y in matrix matrix.

    :param matrix: np.array matrix
    :param x: int x coordinate
    :param y: int y coordinate
    :return: The Second Central difference of a given x and y in matrix matrix
    """
    x1 = (matrix[x + 1, y] - 2 * matrix[x, y] + matrix[x - 1, y])
    y1 = (matrix[x, y + 1] - 2 * matrix[x, y] + matrix[x, y - 1])

    return x1 + y1