# otp.math.atn2

### atn2(y, x)

Returns the principal value of inverse trigonometric function `arctan` of `y/x`.

* **Parameters:**
  * **y** (int, float, [`decimal`](https://docs.pip.distribution.sol.onetick.com/api/types/decimal.html.md#onetick.py.decimal), [`Operation`](https://docs.pip.distribution.sol.onetick.com/api/operation/root.html.md#onetick.py.Operation), [`Column`](https://docs.pip.distribution.sol.onetick.com/api/operation/root.html.md#onetick.py.Column))
  * **x** (int, float, [`decimal`](https://docs.pip.distribution.sol.onetick.com/api/types/decimal.html.md#onetick.py.decimal), [`Operation`](https://docs.pip.distribution.sol.onetick.com/api/operation/root.html.md#onetick.py.Operation), [`Column`](https://docs.pip.distribution.sol.onetick.com/api/operation/root.html.md#onetick.py.Column))
* **Return type:**
  [`Operation`](https://docs.pip.distribution.sol.onetick.com/api/operation/root.html.md#onetick.py.Operation)

### Examples

```pycon
>>> data = otp.Tick(A=1)
>>> data['ATN2'] = otp.math.atn2(1, 1).round(4)  # should return pi/4 ~ 0.7854
>>> otp.run(data)
        Time  A    ATN2
0 2003-12-01  1  0.7854
```

#### SEE ALSO
**ATN2** OneTick function
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