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Math.atan()

The Math.atan() static method returns the inverse tangent (in radians) of a number, that is

π™ΌπšŠπšπš‘.πšŠπšπšŠπš— ( 𝚑 ) = arctan ( x ) = the unique y ∊ [ βˆ’ Ο€ 2 , Ο€ 2 ] such that tan ( 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

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Syntax

js
Math.atan(x)

Parameters

x

A number.

Return value

The inverse tangent (angle in radians between - Ο€ 2 -\frac{\pi}{2} and Ο€ 2 \frac{\pi}{2} , inclusive) of x. If x is Infinity, it returns Ο€ 2 \frac{\pi}{2} . If x is -Infinity, it returns - Ο€ 2 -\frac{\pi}{2} .

Description

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()

js
Math.atan(-Infinity); // -1.5707963267948966 (-Ο€/2)
Math.atan(-0); // -0
Math.atan(0); // 0
Math.atan(1); // 0.7853981633974483  (Ο€/4)
Math.atan(Infinity); // 1.5707963267948966  (Ο€/2)

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

Note that you may want to avoid the theta function and use Math.atan2() instead, which has a wider range (between -Ο€ and Ο€) and avoids outputting NaN for cases such as when x is 0.

Specifications

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
atan 1 12 1 3 1 18 4 10.1 1 1.0 4.4 1.0 0.10.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/atan