def P(N_c, N_cb, e_t, t, A, N_bb):
    """
    Returns the points :math:`P_1`, :math:`P_2` and :math:`P_3`.

    Parameters
    ----------
    N_c : numeric
        Surround chromatic induction factor :math:`N_{c}`.
    N_cb : numeric
        Chromatic induction factor :math:`N_{cb}`.
    e_t : numeric
        Eccentricity factor :math:`e_t`.
    t : numeric
        Temporary magnitude quantity :math:`t`.
    A : numeric
        Achromatic response  :math:`A` for the stimulus.
    N_bb : numeric
        Chromatic induction factor :math:`N_{bb}`.

    Returns
    -------
    tuple
        Points :math:`P`.

    Examples
    --------
    >>> N_c = 1.0
    >>> N_cb = 1.00030400456
    >>> e_t = 1.1740054728519145
    >>> t = 0.149746202921
    >>> A = 23.9394809667
    >>> N_bb = 1.00030400456
    >>> P(N_c, N_cb, e_t, t, A, N_bb)  # doctest: +ELLIPSIS
    (30162.8908154..., 24.2372054..., 1.05)
    """

    P_1 = ((50000 / 13) * N_c * N_cb * e_t) / t
    P_2 = A / N_bb + 0.305
    P_3 = 21 / 20

    return P_1, P_2, P_3