# Math.atan()

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The Math.atan() function returns the arctangent (in radians) of a number, that is

$Math.atan(x)=arctan(x)= the unique y∊[-π2;π2]such thattan(y)=x\mathtt{\operatorname{Math.atan}(x)} = \arctan(x) = \text{ the unique } \; y \in \left[-\frac{\pi}{2}; \frac{\pi}{2}\right] \, \text{such that} \; \tan(y) = x$

## Syntax

Math.atan(x)

x
A number.

### Return value

The arctangent (in radians) of the given number.

## Description

The Math.atan() method returns a numeric value between $-\frac\left\{\pi\right\}\left\{2\right\}$ and $\frac\left\{\pi\right\}\left\{2\right\}$ radians.

Because atan() is a static method of Math, you always use it as Math.atan(), rather than as a method of a Math object you created (Math is not a constructor).

## Examples

### Using Math.atan()

Math.atan(1);   // 0.7853981633974483
Math.atan(0);   // 0
Math.atan(-0);  // -0

Math.atan(Infinity);   //  1.5707963267948966
Math.atan(-Infinity);  // -1.5707963267948966

// The angle that the line [(0,0);(x,y)] forms with the x-axis in a Cartesian coordinate system
Math.atan(y / x);


Note that you may want to avoid using ±Infinity for stylistic reasons. In this case, Math.atan2() with 0 as the second argument may be a better solution.

## Specifications

Specification Status Comment
ECMAScript Latest Draft (ECMA-262)
The definition of 'Math.atan' in that specification.
Draft
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.atan' in that specification.
Standard
ECMAScript 5.1 (ECMA-262)
The definition of 'Math.atan' in that specification.
Standard
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.

## Browser compatibility

Update compatibility data on GitHub
Desktop Mobile Server Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Chrome Full support 1 Edge Full support 12 Firefox Full support 1 IE Full support 3 Opera Full support Yes Safari Full support Yes WebView Android Full support 1 Chrome Android Full support 18 Firefox Android Full support 4 Opera Android Full support Yes Safari iOS Full support Yes Samsung Internet Android Full support 1.0 nodejs Full support Yes

Full support
Full support