@staticmethod
def sgn(z):
    """
        Compute the sign function :math:`\\mathrm{sgn}(z)` factor for
        deflection as sugggested by Bray (1984). For current implementation, returning 1 is sufficient.

        :param z: Complex variable :math:`z = x + \\mathrm{i}y`
        :type z: ``complex``
        :return: :math:`\\mathrm{sgn}(z)`
        :rtype: ``float``
        """
    return 1.0
