def gdx_isnan(val,gdxf):
    """
    Utility function for equating the GDX special values that map to None or NaN
    (which are indistinguishable in pandas).

    Parameters
    ----------
    val : numeric
        value to test
    gdxf : GdxFile
        GDX file containing the value. Provides np_to_gdx_svs map.

    Returns
    -------
    bool
        True if val is a GDX encoded special value that maps to None or numpy.nan;
        False otherwise
    """
    return val in [gdxf.np_to_gdx_svs[0],gdxf.np_to_gdx_svs[1]]