def prop0(T, P):
    """Ideal gas properties

    Parameters
    ----------
    T : float
        Temperature, [K]
    P : float
        Pressure, [MPa]

    Returns
    -------
    prop : dict
        Dict with calculated properties. The available properties are:

            * v: Specific volume, [m³/kg]
            * h: Specific enthalpy, [kJ/kg]
            * s: Specific entropy, [kJ/kgK]
            * cp: Specific isobaric heat capacity, [kJ/kgK]
            * cv: Specific isocoric heat capacity, [kJ/kgK]
            * w: Speed of sound, [m/s]
            * alfav: Cubic expansion coefficient, [1/K]
            * kt: Isothermal compressibility, [1/MPa]
    """
    if T <= 1073.15:
        Tr = 540/T
        Pr = P/1.
        go, gop, gopp, got, gott, gopt = Region2_cp0(Tr, Pr)
    else:
        Tr = 1000/T
        Pr = P/1.
        go, gop, gopp, got, gott, gopt = Region5_cp0(Tr, Pr)

    prop0 = {}
    prop0["v"] = Pr*gop*R*T/P/1000
    prop0["h"] = Tr*got*R*T
    prop0["s"] = R*(Tr*got-go)
    prop0["cp"] = -R*Tr**2*gott
    prop0["cv"] = R*(-Tr**2*gott-1)

    prop0["w"] = (R*T*1000/(1+1/Tr**2/gott))**0.5
    prop0["alfav"] = 1/T
    prop0["xkappa"] = 1/P
    return prop0
Ideal gas properties

    Parameters
    ----------
    T : float
        Temperature, [K]
    P : float
        Pressure, [MPa]

    Returns
    -------
    prop : dict
        Dict with calculated properties. The available properties are:

            * v: Specific volume, [m³/kg]
            * h: Specific enthalpy, [kJ/kg]
            * s: Specific entropy, [kJ/kgK]
            * cp: Specific isobaric heat capacity, [kJ/kgK]
            * cv: Specific isocoric heat capacity, [kJ/kgK]
            * w: Speed of sound, [m/s]
            * alfav: Cubic expansion coefficient, [1/K]
            * kt: Isothermal compressibility, [1/MPa]