Notes
    -----
    This function computes a discrete version of the Hankel transform

    .. math::

        a(r) = \int_{0}^{\infty} \! A(k) \, J_\mu(kr) \, r \, dk \;,

    where :math:`J_\mu` is the Bessel function of order :math:`\mu`.  The index
    :math:`\mu` may be any real number, positive or negative.

    See `fht` for further details.

    r