MySQL Tutorial/Math Numeric Functions/ACOS

ACOS(X) returns the arc cosine of X.

mysql>
ACOS(X)returns NULL if X is not in the range -1 to 1.
mysql>
mysql> SELECT ACOS(1);
+---------+
| ACOS(1) |
+---------+
|       0 |
+---------+
1 row in set (0.00 sec)
mysql> SELECT ACOS(0);
+-----------------+
| ACOS(0)         |
+-----------------+
| 1.5707963267949 |
+-----------------+
1 row in set (0.00 sec)
mysql>

SELECT ACOS(1.0001);

mysql>
mysql>
mysql> SELECT ACOS(1.0001);
+--------------+
| ACOS(1.0001) |
+--------------+
|         NULL |
+--------------+
1 row in set (0.01 sec)
mysql>