def get_absolute_airmass(airmass_relative, pressure=101325.0):
    """
    Determine absolute (pressure corrected) airmass from relative
    airmass and pressure

    Gives the airmass for locations not at sea-level (i.e. not at
    standard pressure). The input argument "AMrelative" is the relative
    airmass. The input argument "pressure" is the pressure (in Pascals)
    at the location of interest and must be greater than 0. The
    calculation for absolute airmass is

    .. math::
        absolute airmass = (relative airmass)*pressure/101325

    Parameters
    ----------
    airmass_relative : numeric
        The airmass at sea-level.

    pressure : numeric, default 101325
        The site pressure in Pascal.

    Returns
    -------
    airmass_absolute : numeric
        Absolute (pressure corrected) airmass

    References
    ----------
    .. [1] C. Gueymard, "Critical analysis and performance assessment of
       clear sky solar irradiance models using theoretical and measured
       data," Solar Energy, vol. 51, pp. 121-138, 1993.
    """
    airmass_absolute = airmass_relative * pressure / 101325.0
    return airmass_absolute
