def vapour_pressure(Temperature, element):
    r"""Return the vapour pressure of rubidium or cesium in Pascals.

    This function receives as input the temperature in Kelvins and the
    name of the element.

    >>> print vapour_pressure(25.0 + 273.15,"Rb")
    5.31769896107e-05
    >>> print vapour_pressure(39.3 + 273.15,"Rb")
    0.000244249795696
    >>> print vapour_pressure(90.0 + 273.15,"Rb")
    0.0155963687128
    >>> print vapour_pressure(25.0 + 273.15,"Cs")
    0.000201461144963
    >>> print vapour_pressure(28.5 + 273.15,"Cs")
    0.000297898928349
    >>> print vapour_pressure(90.0 + 273.15,"Cs")
    0.0421014384667

    The element must be in the database.

    >>> print vapour_pressure(90.0 + 273.15,"Ca")
    Traceback (most recent call last):
    ...
    ValueError: Ca is not an element in the database for this function.

    References:
    [1] Daniel A. Steck, "Cesium D Line Data," available online at
        http://steck.us/alkalidata (revision 2.1.4, 23 December 2010).
    [2] Daniel A. Steck, "Rubidium 85 D Line Data," available online at
        http://steck.us/alkalidata (revision 2.1.5, 19 September 2012).
    [3] Daniel A. Steck, "Rubidium 87 D Line Data," available online at
        http://steck.us/alkalidata (revision 2.1.5, 19 September 2012).
    """
    if element == "Rb":
        Tmelt = 39.30+273.15  # K.
        if Temperature < Tmelt:
            P = 10**(2.881+4.857-4215.0/Temperature)  # Torr.
        else:
            P = 10**(2.881+4.312-4040.0/Temperature)  # Torr.
    elif element == "Cs":
        Tmelt = 28.5 + 273.15  # K.
        if Temperature < Tmelt:
            P = 10**(2.881+4.711-3999.0/Temperature)  # Torr.
        else:
            P = 10**(2.881+4.165-3830.0/Temperature)  # Torr.
    else:
        s = str(element)
        s += " is not an element in the database for this function."
        raise ValueError(s)

    P = P * 101325.0/760.0  # Pascals.
    return P
def vapour_pressure ( Temperature , element ) : if element == "Rb" : Tmelt = 39.30 + 273.15 if Temperature < Tmelt : P = 10 ** ( 2.881 + 4.857 - 4215.0 / Temperature ) else : P = 10 ** ( 2.881 + 4.312 - 4040.0 / Temperature ) elif element == "Cs" : Tmelt = 28.5 + 273.15 if Temperature < Tmelt : P = 10 ** ( 2.881 + 4.711 - 3999.0 / Temperature ) else : P = 10 ** ( 2.881 + 4.165 - 3830.0 / Temperature ) else : s = str ( element ) s += " is not an element in the database for this function." raise ValueError ( s ) P = P * 101325.0 / 760.0 return P
r"""Return the vapour pressure of rubidium or cesium in Pascals.

    This function receives as input the temperature in Kelvins and the
    name of the element.

    >>> print vapour_pressure(25.0 + 273.15,"Rb")
    5.31769896107e-05
    >>> print vapour_pressure(39.3 + 273.15,"Rb")
    0.000244249795696
    >>> print vapour_pressure(90.0 + 273.15,"Rb")
    0.0155963687128
    >>> print vapour_pressure(25.0 + 273.15,"Cs")
    0.000201461144963
    >>> print vapour_pressure(28.5 + 273.15,"Cs")
    0.000297898928349
    >>> print vapour_pressure(90.0 + 273.15,"Cs")
    0.0421014384667

    The element must be in the database.

    >>> print vapour_pressure(90.0 + 273.15,"Ca")
    Traceback (most recent call last):
    ...
    ValueError: Ca is not an element in the database for this function.

    References:
    [1] Daniel A. Steck, "Cesium D Line Data," available online at
        http://steck.us/alkalidata (revision 2.1.4, 23 December 2010).
    [2] Daniel A. Steck, "Rubidium 85 D Line Data," available online at
        http://steck.us/alkalidata (revision 2.1.5, 19 September 2012).
    [3] Daniel A. Steck, "Rubidium 87 D Line Data," available online at
        http://steck.us/alkalidata (revision 2.1.5, 19 September 2012).