ACOS

Description

Returns the arc cosine of x, or NULL if x is not in the range -1 to 1.

Syntax

ACOS(<x>)

Parameters

Parameter	Description
<x>	The value for which the arc cosine is to be calculated

Return Value

The arc cosine value of parameter x, expressed in radians.

Special Cases

• When x equals 1, returns 0
• When x equals 0, returns π/2
• When x equals -1, returns π
• When x is not in the range [-1, 1], returns NULL
• When x is NaN, returns NaN
• When x is positive or negative infinity, returns NULL
• When x is NULL, returns NULL

Examples

select acos(1);

+-----------+
| acos(1.0) |
+-----------+
|         0 |
+-----------+

select acos(0);

+--------------------+
| acos(0.0)          |
+--------------------+
| 1.5707963267948966 |
+--------------------+

select acos(-1);

+--------------------+
| acos(-1.0)         |
+--------------------+
| 3.141592653589793  |
+--------------------+

select acos(-2);

+------------+
| acos(-2.0) |
+------------+
|       NULL |
+------------+

select acos(1.0000001);

+-----------------+
| acos(1.0000001) |
+-----------------+
|            NULL |
+-----------------+

select acos(cast('nan' as double));

+---------------------------+
| acos(cast('nan' AS DOUBLE)) |
+---------------------------+
| NaN                       |
+---------------------------+

select acos(cast('inf' as double));

+---------------------------+
| acos(cast('inf' AS DOUBLE)) |
+---------------------------+
| NULL                      |
+---------------------------+