@Description("arc cosine")
    @ScalarFunction
    @SqlType(StandardTypes.DOUBLE)
    public static double acos(@SqlType(StandardTypes.DOUBLE) double num)
    {
        return Math.acos(num);
    }
@Test
    public void testAcos()
    {
        for (double doubleValue : DOUBLE_VALUES) {
            assertFunction("acos(" + doubleValue + ")", DOUBLE, Math.acos(doubleValue));
            assertFunction("acos(REAL '" + (float) doubleValue + "')", DOUBLE, Math.acos((float) doubleValue));
        }
        assertFunction("acos(NULL)", DOUBLE, null);
    }