def cross_product_compare(start, candidate1, candidate2):
    """Compare two relative changes by their cross-product.

    This is meant to be a way to determine which vector is more "inside"
    relative to ``start``.

    .. note::

       This is a helper for :func:`_simple_convex_hull`.

    Args:
        start (numpy.ndarray): The start vector (as 1D NumPy array with
            2 elements).
        candidate1 (numpy.ndarray): The first candidate vector (as 1D
            NumPy array with 2 elements).
        candidate2 (numpy.ndarray): The second candidate vector (as 1D
            NumPy array with 2 elements).

    Returns:
        float: The cross product of the two differences.
    """
    delta1 = candidate1 - start
    delta2 = candidate2 - start
    return cross_product(delta1, delta2)
Compare two relative changes by their cross-product.

    This is meant to be a way to determine which vector is more "inside"
    relative to ``start``.

    .. note::

       This is a helper for :func:`_simple_convex_hull`.

    Args:
        start (numpy.ndarray): The start vector (as 1D NumPy array with
            2 elements).
        candidate1 (numpy.ndarray): The first candidate vector (as 1D
            NumPy array with 2 elements).
        candidate2 (numpy.ndarray): The second candidate vector (as 1D
            NumPy array with 2 elements).

    Returns:
        float: The cross product of the two differences.