ATAN2
描述
返回 'y' / 'x' 的反正切。
语法
ATAN2(<y>, <x>)
参数
| 参数 | 说明 |
|---|---|
<x> | 参与计算的反正切的值，表示水平坐标（或 x 值），从原点 (0,0) 沿 x 轴的距离。 |
<y> | 参与计算的反正切的值，表示垂直坐标（或 y 值），从原点 (0,0) 沿 y 轴的距离。 |
返回值
参数 y / x 的反正切值
特殊情况
- 若
y或x为NaN，返回NaN - 当
x > 0且y = ±0.0，返回±0（符号同y） - 当
x = 0.0（含+0.0与-0.0）且y > 0，返回π/2（约 1.570796326794897） - 当
x = 0.0（含+0.0与-0.0）且y < 0，返回-π/2（约 -1.570796326794897） - 当
x < 0且y = +0.0，返回π（约 3.141592653589793）；当x < 0且y = -0.0，返回-π - 当
y = +∞、x有限，返回π/2；当y = -∞、x有限，返回-π/2 - 当
y = +∞且x = +∞，返回π/4（约 0.7853981633974483） - 当
y = -∞且x = +∞，返回-π/4（约 -0.7853981633974483） - 当
y = +∞且x = -∞，返回3π/4（约 2.356194490192345） - 当
y = -∞且x = -∞，返回-3π/4（约 -2.356194490192345） - 当
x = +∞且y有限为正，返回0；当x = +∞且y有限为负，返回-0 - 当
x = -∞且y有限为正，返回π；当x = -∞且y有限为负，返回-π - 当
y或x为NULL，返回NULL
举例
select atan2(0.1, 0.2);
+---------------------+
| atan2(0.1, 0.2) |
+---------------------+
| 0.46364760900080609 |
+---------------------+
select atan2(1.0, 1.0);
+---------------------+
| atan2(1.0, 1.0) |
+---------------------+
| 0.78539816339744828 |
+---------------------+
select atan2(cast('nan' as double), 1.0);
+----------------------------------+
| atan2(cast('nan' AS DOUBLE), 1.0)|
+----------------------------------+
| NaN |
+----------------------------------+
select atan2(1.0, cast('nan' as double));
+----------------------------------+
| atan2(1.0, cast('nan' AS DOUBLE))|
+----------------------------------+
| NaN |
+----------------------------------+
select atan2(0.0, 1.0);
+----------------+
| atan2(0.0, 1.0)|
+----------------+
| 0 |
+----------------+
select atan2(-0.0, 1.0);
+-----------------+
| atan2(-0.0, 1.0)|
+-----------------+
| -0 |
+-----------------+
select atan2(0.0, -1.0);
+-----------------+
| atan2(0.0, -1.0)|
+-----------------+
| 3.141592653589793|
+------------------+
select atan2(-0.0, -1.0);
+------------------+
| atan2(-0.0, -1.0)|
+------------------+
| -3.141592653589793|
+-------------------+
select atan2(1.0, 0.0);
+----------------+
| atan2(1.0, 0.0)|
+----------------+
| 1.570796326794897 |
+--------------------+
select atan2(-1.0, 0.0);
+-----------------+
| atan2(-1.0, 0.0)|
+-----------------+
| -1.570796326794897 |
+---------------------+
select atan2(cast('inf' as double), cast('-inf' as double));
+--------------------------------------------+
| atan2(cast('inf' AS DOUBLE), cast('-inf' AS DOUBLE)) |
+--------------------------------------------+
| 2.356194490192345 |
+--------------------------------------------+
select atan2(cast('-inf' as double), cast('inf' as double));
+-------------------------------------------+
| atan2(cast('-inf' AS DOUBLE), cast('inf' AS DOUBLE)) |
+-------------------------------------------+
| -0.7853981633974483 |
+-------------------------------------------+
select atan2(1.0, cast('-inf' as double));
+----------------------------------+
| atan2(1.0, cast('-inf' AS DOUBLE))|
+----------------------------------+
| 3.141592653589793 |
+----------------------------------+
select atan2(-1.0, cast('inf' as double));
+---------------------------------+
| atan2(-1.0, cast('inf' AS DOUBLE))|
+---------------------------------+
| -0 |
+---------------------------------+
