def Edalat(T, Tc, Pc, omega):
tau = <NUM_LIT:1.> - T/Tc<EOL>a = -<NUM_LIT> - <NUM_LIT>*omega<EOL>c = -<NUM_LIT> - <NUM_LIT>*omega<EOL>d = <NUM_LIT:1.>/(-<NUM_LIT> - <NUM_LIT>*omega + <NUM_LIT>*omega**<NUM_LIT:2>)<EOL>b = <NUM_LIT> - <NUM_LIT>*omega - <NUM_LIT>*d<EOL>lnPr = (a*tau + b*tau**<NUM_LIT> + c*tau**<NUM_LIT:3> + d*tau**<NUM_LIT:6>)/(<NUM_LIT:1.>-tau)<EOL>return exp(lnPr)*Pc<EOL>
r'''Calculates vapor pressure of a fluid at arbitrary temperatures using a
    CSP relationship by [1]_. Requires a chemical's critical temperature,
    pressure, and acentric factor. Claimed to have a higher accuracy than the
    Lee-Kesler CSP relationship.

    The vapor pressure of a chemical at `T` is given by:

    .. math::
        \ln(P^{sat}/P_c) = \frac{a\tau + b\tau^{1.5} + c\tau^3 + d\tau^6}
        {1-\tau}

        a = -6.1559 - 4.0855\omega

        b = 1.5737 - 1.0540\omega - 4.4365\times 10^{-3} d

        c = -0.8747 - 7.8874\omega

        d = \frac{1}{-0.4893 - 0.9912\omega + 3.1551\omega^2}

        \tau = 1 - \frac{T}{T_c}

    Parameters
    ----------
    T : float
        Temperature of fluid [K]
    Tc : float
        Critical temperature of fluid [K]
    Pc : float
        Critical pressure of fluid [Pa]
    omega : float
        Acentric factor [-]

    Returns
    -------
    Psat : float
        Vapor pressure, [Pa]

    Notes
    -----
    [1]_ found an average error of 6.06% on 94 compounds and 1106 data points.

    Examples
    --------
    >>> Edalat(347.2, 617.1, 36E5, 0.299)
    13461.273080743307

    References
    ----------
    .. [1] Edalat, M., R. B. Bozar-Jomehri, and G. A. Mansoori. "Generalized 
       Equation Predicts Vapor Pressure of Hydrocarbons." Oil and Gas Journal; 
       91:5 (February 1, 1993).