# Math.atan()

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
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