def mnsi(b3, b4, b6, b8):
    """
    Misra Non-such Index (Misra, Wheeler, and Oliver, 1977).

    .. math:: MNSI = 0.404 * b3 + 0.039 * b4 - 0.505 * b6 + 0.762 * b8

    :param b3: Green.
    :type b3: numpy.ndarray or float
    :param b4: Red.
    :type b4: numpy.ndarray or float
    :param b6: Red-edge 2.
    :type b6: numpy.ndarray or float
    :param b8: NIR.
    :type b8: numpy.ndarray or float

    :returns MNSI: Index value

    .. Tip::

        Misra, P. N., Wheeler, S. G., Oliver, R. E. 1977. Kauth-Thomas \
        brightness and greenness axes. in: Contract NASA 9-14350, 23-46.
    """

    MNSI = 0.404 * b3 + 0.039 * b4 - 0.505 * b6 + 0.762 * b8
    return MNSI