@Description("test if value is not-a-number")
    @ScalarFunction("is_nan")
    @SqlType(StandardTypes.BOOLEAN)
    public static boolean isNaN(@SqlType(StandardTypes.DOUBLE) double num)
    {
        return Double.isNaN(num);
    }
@Test
    public void testIsNaN()
    {
        assertFunction("is_nan(0.0E0 / 0.0E0)", BOOLEAN, true);
        assertFunction("is_nan(0.0E0 / 1.0E0)", BOOLEAN, false);
        assertFunction("is_nan(infinity() / infinity())", BOOLEAN, true);
        assertFunction("is_nan(nan())", BOOLEAN, true);
        assertFunction("is_nan(REAL '0.0' / REAL '0.0')", BOOLEAN, true);
        assertFunction("is_nan(REAL '0.0' / 1.0E0)", BOOLEAN, false);
        assertFunction("is_nan(infinity() / infinity())", BOOLEAN, true);
        assertFunction("is_nan(nan())", BOOLEAN, true);
        assertFunction("is_nan(NULL)", BOOLEAN, null);
    }