The ACOS function calculates the arccosine of a number. This topic describes the syntax and parameters of the ACOS function. This topic also provides examples on how to use the ACOS function.
Syntax
double|decimal acos(<number>)Parameters
number: required. The value ranges from -1 to 1. A value of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, the value is implicitly converted into a value of the DOUBLE type before calculation.
Return value
The data type of the return value depends on the data type of the input parameter. The value ranges from 0 to π. The return value varies based on the following rules:
If the value of number is of the DOUBLE or DECIMAL type, a value of the same type is returned.
If the value of number is of the STRING or BIGINT type, a value of the DOUBLE type is returned.
If the value of number does not fall into the range from -1 to 1, null is returned.
If the value of number is null, null is returned.
Sample data
This section provides sample source data and examples for you to understand how to use the function. In this topic, a table named mf_math_fun_t is created and data is inserted into the table. Sample statements:
create table if not exists mf_math_fun_t(
int_data int,
bigint_data bigint,
double_data double,
decimal_data decimal,
float_data float,
string_data string
);
insert into mf_math_fun_t values
(null, -10, 0.525, 0.525BD, cast(0.525 as float), '10'),
(-20, null, -0.1, -0.1BD, cast(-0.1 as float), '-10'),
(0, -1, null, 20.45BD, cast(-1 as float), '30'),
(-40, 4, 0.89, null, cast(0.89 as float), '-30'),
(5, -50, -1, -1BD, null, '50'),
(-60, 6, 1.5, 1.5BD, cast(1.5 as float), '-50'),
(-1, -70, -7.5, -7.5BD, cast(-7.5 as float),null ),
(-80, 1, -10.2, -10.2BD, cast(-10.2 as float), '-1' ),
(9, -90, 2.58, 2.58BD, cast(2.58 as float), '0'),
(-100, 10, -5.8, -5.8BD, cast(-5.8 as float), '-90');Query data from the mf_math_fun_t table. Sample statement:
select * from mf_math_fun_t;
-- The following result is returned:
+------------+-------------+-------------+--------------+------------+-------------+
| int_data | bigint_data | double_data | decimal_data | float_data | string_data |
+------------+-------------+-------------+--------------+------------+-------------+
| NULL | -10 | 0.525 | 0.525 | 0.525 | 10 |
| -20 | NULL | -0.1 | -0.1 | -0.1 | -10 |
| 0 | -1 | NULL | 20.45 | -1.0 | 30 |
| -40 | 4 | 0.89 | NULL | 0.89 | -30 |
| 5 | -50 | -1.0 | -1 | NULL | 50 |
| -60 | 6 | 1.5 | 1.5 | 1.5 | -50 |
| -1 | -70 | -7.5 | -7.5 | -7.5 | NULL |
| -80 | 1 | -10.2 | -10.2 | -10.2 | -1 |
| 9 | -90 | 2.58 | 2.58 | 2.58 | 0 |
| -100 | 10 | -5.8 | -5.8 | -5.8 | -90 |
+------------+-------------+-------------+--------------+------------+-------------+Example: static data
-- The return value is 0.5155940062460905.
select acos("0.87");
-- The return value is 1.5707963267948966.
select acos(0);
-- The return value is null.
select acos(null);Example: table data
Calculate the arccosine based on sample data. Sample statement:
select acos(bigint_data) as bigint_new, acos(double_data) as double_new, acos(decimal_data) as decimal_new, acos(string_data) as string_new from mf_math_fun_t;The following result is returned:
+-------------------+--------------------+--------------------+---------------------+
| bigint_new | double_new | decimal_new | string_new |
+-------------------+--------------------+--------------------+---------------------+
| NULL | 1.0180812136981134 | 1.0180812136981134 | NULL |
| NULL | 1.6709637479564565 | 1.6709637479564565 | NULL |
| 3.141592653589793 | NULL | NULL | NULL |
| NULL | 0.4734511572720662 | NULL | NULL |
| NULL | 3.141592653589793 | 3.141592653589793 | NULL |
| NULL | NULL | NULL | NULL |
| NULL | NULL | NULL | NULL |
| 0.0 | NULL | NULL | 3.141592653589793 |
| NULL | NULL | NULL | 1.5707963267948966 |
| NULL | NULL | NULL | NULL |
+-------------------+--------------------+--------------------+---------------------+Related functions
ACOS is a mathematical function. For more information about functions related to data computing and conversion, see Mathematical functions.