---
title: atan
card_id: 52019
---

# atan

```
the atan of [ph:number]
```

Value returned: number equal to the trigonometric arc tangent of `[ph:number]` expressed in radians

Note: There are 2 * pi radians in 360 degrees.

## Examples

```
the atan of 0
the atan of 1 -- returns pi/4, or 0.785398, radians

the atan of 1 + pi -- returns 5/4 pi, or 3.926991
the atan of (1 + pi) -- returns 1.333878
```

## Related Topics

* [cos](/HyperTalkReference/functions/cos)
* [numberFormat](/HyperTalkReference/properties/numberFormat)
* [sin](/HyperTalkReference/functions/sin)
* [tan](/HyperTalkReference/functions/tan)