acos
description
Syntax
DOUBLE acos(DOUBLE x)
返回x的反余弦值，若 x不在-1到 1的范围之内，则返回 NULL.
example
mysql> select acos(1);
+-----------+
| acos(1.0) |
+-----------+
| 0 |
+-----------+
mysql> select acos(0);
+--------------------+
| acos(0.0) |
+--------------------+
| 1.5707963267948966 |
+--------------------+
mysql> select acos(-2);
+------------+
| acos(-2.0) |
+------------+
| nan |
+------------+keywords
ACOS