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Math.atan()

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

Math.atan ( x ) = arctan ( x ) = the unique y [ - π 2 ; π 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

Math.atan(x)

Parameters

x

A number.

Return value

The arctangent (in radians) of the given number.

Description

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

Browser compatibility

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