---
title: ES|QL ATAN function
description: 
url: https://www.elastic.co/docs/reference/query-languages/esql/functions-operators/math-functions/atan
products:
  - Elasticsearch
---

# ES|QL ATAN function
## Syntax

![Embedded](https://www.elastic.co/docs/reference/query-languages/esql/images/generated/x-pack-esql/functions/atan.svg)


## Parameters

<definitions>
  <definition term="number">
    Numeric expression. If `null`, the function returns `null`.
  </definition>
</definitions>


## Description

Returns the [arctangent](https://en.wikipedia.org/wiki/Inverse_trigonometric_functions) of the input numeric expression as an angle, expressed in radians.

## Supported types


| number        | result |
|---------------|--------|
| double        | double |
| integer       | double |
| long          | double |
| unsigned_long | double |


## Example

```esql
ROW a=12.9
| EVAL atan=ATAN(a)
```


| a:double | atan:double        |
|----------|--------------------|
| 12.9     | 1.4934316673669235 |