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