The ATAN function returns the arctangent (in radians) of a given number.

This function takes a single Number as input. It outputs another Number: the arctangent, in radians, of the given number.

### Declaration

``````ATAN(number) -> arctangent
``````

### Parameters

number (required, type: `Number`)
Any number.

### Return Values

arctangent (type: `Number`)
The arctangent, in radians, of the given number.

### Examples

The following example returns the arctangent of 1. Note that the arctangent of one is forty-five degrees, or 0.25π radians, but the ATAN function doesn't output an angle in degrees or in radians in terms of pi. Rather, it provides a numerical estimation of the angle in radians:

``````ATAN(1) -> 0.7853981633974483
``````

To calculate the arctangent in degrees, the ATAN function must be used in tandem with the DEGREES function, such as in the following example:

``````DEGREES(ATAN(1)) -> 45
``````

ATAN can also be used in tandem with the PI function to provide insight into how the angle in radians relates to terms of pi, such as in the following example:

``````ATAN(1)/PI() -> 0.25
``````