Syntax
ACOS(X)
Purpose
ACOS() returns the arc cosine of X. If the value of X is outside the range of [-1,1], the function returns NULL.
Examples
obclient> SELECT ACOS(-10), ACOS(0), ACOS(10), ACOS(-0.5), ACOS(0.5);
+-----------+--------------------+----------+--------------------+--------------------+
| ACOS(-10) | ACOS(0) | ACOS(10) | ACOS(-0.5) | ACOS(0.5) |
+-----------+--------------------+----------+--------------------+--------------------+
| NULL | 1.5707963267948966 | NULL | 2.0943951023931957 | 1.0471975511965979 |
+-----------+--------------------+----------+--------------------+--------------------+
1 row in set