# ATAN function
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ATAN is a trigonometric function that returns the arc tangent of a number. The return value is in radians and is between `-PI` and `PI`.

## Syntax
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```
ATAN(number)
```

## Arguments
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 *number*   
The input parameter is a `DOUBLE PRECISION` number. 

## Return type
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`DOUBLE PRECISION`

## Examples
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To return the arc tangent of `1` and multiply it by 4, use the following example.

```
SELECT ATAN(1) * 4 AS pi;
            
+-------------------+
|        pi         |
+-------------------+
| 3.141592653589793 |
+-------------------+
```