mathjs/docs/reference/functions/atan.md

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser and offers an integrated solution to work with numbers, big numbers, complex numbers, units, and matrices.

# Function atan

Calculate the inverse tangent of a value.

For matrices, the function is evaluated element wise.


## Syntax

```js
math.atan(x)
```

### Parameters

Parameter | Type | Description
--------- | ---- | -----------
`x` | Number | BigNumber | Boolean | Complex | Array | Matrix | null | Function input

### Returns

Type | Description
---- | -----------
Number | BigNumber | Complex | Array | Matrix | The arc tangent of x


## Examples

```js
math.atan(0.5);           // returns Number 0.4636476090008061
math.atan(math.tan(1.5)); // returns Number 1.5

math.atan(2);             // returns Complex 1.5707963267948966 -1.3169578969248166 i
```


## See also

[tan](tan.md),
[asin](asin.md),
[acos](acos.md)


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