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 nan.

example

1. mysql> select acos(1);
2. +-----------+
3. | acos(1.0) |
4. +-----------+
5. |         0 |
6. +-----------+
7. mysql> select acos(0);
8. +--------------------+
9. | acos(0.0)          |
10. +--------------------+
11. | 1.5707963267948966 |
12. +--------------------+
13. mysql> select acos(-2);
14. +------------+
15. | acos(-2.0) |
16. +------------+
17. |        nan |
18. +------------+

keywords

1. ACOS