Returns the arccosine of a number as a value in radians in the range [0, pi].
Syntax
double|decimal acos(<number>)Parameters
| Parameter | Required | Type | Description |
|---|---|---|---|
number | Yes | DOUBLE or DECIMAL | The input value. Must be in the range [-1, 1]. STRING and BIGINT values are implicitly converted to DOUBLE before calculation. |
Return value
The return type matches the input type, except that STRING and BIGINT inputs return DOUBLE.
| Input type | Return type | Condition |
|---|---|---|
| DOUBLE | DOUBLE | Input is in [-1, 1] |
| DECIMAL | DECIMAL | Input is in [-1, 1] |
| STRING | DOUBLE | Input is in [-1, 1] |
| BIGINT | DOUBLE | Input is in [-1, 1] |
| Any | null | Input is outside [-1, 1] |
| Any | null | Input is null |
Sample data
The examples in this topic use the mf_math_fun_t table. To create and populate the table, run the following 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 the table to confirm the data:
select * from mf_math_fun_t;Result:
+------------+-------------+-------------+--------------+------------+-------------+
| 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 |
+------------+-------------+-------------+--------------+------------+-------------+Examples
Static values
-- Returns 0.5155940062460905
select acos("0.87");
-- Returns 1.5707963267948966
select acos(0);
-- Returns null (input is null)
select acos(null);
-- Returns null (input is out of range)
select acos(2);Table data
Calculate the arccosine of values in the mf_math_fun_t table:
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;Result:
+-------------------+--------------------+--------------------+---------------------+
| 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 |
+-------------------+--------------------+--------------------+---------------------+NULL in bigint_new, double_new, decimal_new, and string_new indicates that the input value was outside the range [-1, 1] or was null.
Related functions
ACOS is a mathematical function. For more information about related functions, see Mathematical functions.
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