# ATan

__Value__ **= ATan (** __Number__ **)**
__Value__ **= Atn (** __Number__ **)**

The Atn function is the inverse of the Tan function. It computes the arc-tangent of a number. That return value is in radians and in the range from -π/2 to π/2 radians (-90 to 90 degrees)

To convert from degrees to radians, multiply degrees by π/180. To convert from radians to degrees, multiply radians by 180/π.
Or better use the Deg or Rad functions!

### Examples

The arc-tangent can be used to calculate the value for π as shown below:

**Print** "The Value of Pi = "**;** **4** ***** **Atn****(****1****)**

```
The Value of Pi = 3.14159265359
```

There is another function Ang (alias ATan2) which takes two arguments and returns the angle correctly over 4 quadrants.

### See also