# ATAN

The ATAN function returns the arctangent of a numeric expression as an angle in radians.

## Syntax

`ATAN(number)`

### Parameters

#### number

Numeric expression for which to calculate the arctangent. If the value is `null`, the function returns `null`.

## Examples

Calculates the arctangent of the value in column `a` and stores the result in a new column called `atan`:

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