Compute standard cost matrices of size (n,n) for OT problems

    Parameters
    ----------

    n : int
        size of the cost matrix
    method : str, optional
        Type of loss matrix chosen from:

        * 'lin_square' : linear sampling between 0 and n-1, quadratic loss


    Returns
    -------

    M : np.array (n1,n2)
        distance matrix computed with given metric

def dist0(n, method='lin_square'):
    """Compute standard cost matrices of size (n,n) for OT problems

    Parameters
    ----------

    n : int
        size of the cost matrix
    method : str, optional
        Type of loss matrix chosen from:

        * 'lin_square' : linear sampling between 0 and n-1, quadratic loss


    Returns
    -------

    M : np.array (n1,n2)
        distance matrix computed with given metric


    """
    res = 0
    if method == 'lin_square':
        x = np.arange(n, dtype=np.float64).reshape((n, 1))
        res = dist(x, x)
    return res