LOG2

描述

返回以2为底的x的自然对数。

语法

LOG2(<x>)

参数

参数	说明
<x>	真数 必须大于 0

返回值

返回一个浮点数。特殊情况：

• 当 x 为 NULL 时，返回 NULL
• 当 x 为 NaN 时，返回 NaN

举例

select log2(1);

+-------------------------+
| log2(cast(1 as DOUBLE)) |
+-------------------------+
|                     0.0 |
+-------------------------+

select log2(2);

+-------------------------+
| log2(cast(2 as DOUBLE)) |
+-------------------------+
|                     1.0 |
+-------------------------+

select log2(10);

+--------------------------+
| log2(cast(10 as DOUBLE)) |
+--------------------------+
|       3.3219280948873626 |
+--------------------------+

select log2(NULL);

+------------+
| log2(NULL) |
+------------+
|       NULL |
+------------+

select log2(cast('Nan' as double));

+-----------------------------+
| log2(cast('Nan' as double)) |
+-----------------------------+
|                         NaN |
+-----------------------------+