def p(parallel):
    """ adds elements in parallel

    Notes
    ---------
    .. math::

        Z = \\frac{1}{\\frac{1}{Z_1} + \\frac{1}{Z_2} + ... + \\frac{1}{Z_n}}

     """
    z = len(parallel[0]) * [0 + 0 * 1.0j]
    for elem in parallel:
        z += 1 / elem
    return 1 / z
