def is_non_descending(knot_vector):
    """
    Check whether a knot vector is in non-descending order.

    Arguments
    ---------
    knot_vector : array_like
        The knot vector.

    Returns
    -------
    bool
        True if the knot vector is in non-descending order or False otherwise.
    """
    for i in range(len(knot_vector) - 1):
        if knot_vector[i + 1] < knot_vector[i]:
            return False
    return True