ATAN2

説明

'y' / 'x' の逆正接を返します。

構文

ATAN2(<y>, <x>)

パラメータ

パラメータ	説明
<x>	原点(0,0)からx軸に沿った水平距離（座標）を表す値。
<y>	原点(0,0)からy軸に沿った垂直距離（座標）を表す値。

戻り値

パラメータ y / x のatan2値。

特殊ケース

• yまたはxがNaNの場合、NaNを返す
• x > 0かつy = ±0.0の場合、±0を返す（符号はyに従う）
• x = 0.0（+0.0または-0.0のいずれか）かつy > 0の場合、π/2（約1.570796326794897）を返す
• x = 0.0（+0.0または-0.0のいずれか）かつy < 0の場合、-π/2（約-1.570796326794897）を返す
• x < 0かつy = +0.0の場合、π（約3.141592653589793）を返す；x < 0かつy = -0.0の場合、-πを返す
• y = +Infinityかつxが有限の場合、π/2を返す；y = -Infinityかつxが有限の場合、-π/2を返す
• y = +Infinityかつx = +Infinityの場合、π/4（約0.7853981633974483）を返す
• y = -Infinityかつx = +Infinityの場合、-π/4（約-0.7853981633974483）を返す
• y = +Infinityかつx = -Infinityの場合、3π/4（約2.356194490192345）を返す
• y = -Infinityかつx = -Infinityの場合、-3π/4（約-2.356194490192345）を返す
• x = +Infinityかつ有限のy > 0の場合、0を返す；有限のy < 0の場合、-0を返す
• x = -Infinityかつ有限のy > 0の場合、πを返す；有限のy < 0の場合、-πを返す
• yまたはxがNULLの場合、NULLを返す

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                              |
+---------------------------------+