# ATAN

Returns the arc tangent of expression `x`.

## Format

ATAN(x)## Description

The returned value ranges from $\left[-\pi /2,\pi /2\right]$ . Thus, $-\pi /2\le ATAN\left(x\right)\le \pi /2$ .

## Arguments

`x`- Any valid function expression.

## Example

```
<Reference_Variable
id = "1"
label = "ATAN Example"
type = "EXPRESSION"
expr = "ATAN(AY(569,193))"
/>
```