# Atn()

Arctangent function. The arctangent is the angle whose tangent
is number.

```
Atn( number=number );
```

**Returns:** number

# Arguments

| Argument | Type | Required | Description | Default |
|----------|------|----------|-------------|---------|
| number | number | Yes | Tangent of an angle. Must be between -1 and 1. |  |

# Examples

```cfml
angle_tangent = 1;
dump(Atn(angle_tangent)); // 0.785398163397 in radians
```







# Categories

[Numbers](../../categories/number.md), [Math](../../categories/math.md)

# See Also

[numeric.atn()](../objects/numeric/atn.md)