# ATAN

The ATAN function returns the arctangent of a given numeric expression, expressed in radians.

## Syntax

`ATAN(number)`

### Parameters

#### number

This is a numeric expression. If the parameter is `null`, the function will also return `null`.

## Examples

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

```esql
ROW x=5.0, y=3.0
| EVAL atan_yx = ATAN(y / x)
```
