_median(X, tol=1e-5, max_iter=500):
    &#34;&#34;&#34;Geometric median.

    This code is adapted from [2]_ using the Vardi and Zhang algorithm
    described in [1]_.

    Parameters
    ----------
    X : array, shape=(n_observations, n_variables)
        The data.
    tol : float
        Tolerance (default=1.e-5)
    max_iter : int
        Max number of iterations (default=500):

    Returns
    -------
    y1 : array, shape=(n_variables,)
        Geometric median over X.

    References
    ----------
 