Math.asin()

Summary

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

x[-1;1],Math.asin(x)=arcsin(x)= the unique y[-π2;π2]such thatsin(y)=x\forall x \in [{-1};1],\;\mathtt{\operatorname{Math.asin}(x)} = \arcsin(x) = \text{ the unique } \; y \in \left[-\frac{\pi}{2}; \frac{\pi}{2}\right] \, \text{such that} \; \sin(y) = x

Syntax

Math.asin(x)

Parameters

x
A number.

Description

The asin method returns a numeric value between -π2-\frac{\pi}{2} and π2\frac{\pi}{2} radians for x between -1 and 1. If the value of number is outside this range, it returns NaN.

Because asin is a static method of Math, you always use it as Math.asin(), rather than as a method of a Math object you created.

Examples

Example: Using Math.asin()

Math.asin(-2);  // NaN
Math.asin(-1);  // -1.5707963267948966 (-pi/2)
Math.asin(0);   // 0
Math.asin(0.5); // 0.5235987755982989
Math.asin(1);   // 1.570796326794897 (pi/2)
Math.asin(2);   // NaN

For values less than -1 or greater than 1, Math.asin returns NaN.

Specifications

Specification Status Comment
ECMAScript 1st Edition. Implemented in JavaScript 1.0 Standard Initial definition.
ECMAScript Language Specification 5.1th Edition (ECMA-262) Standard  
ECMAScript Language Specification 6th Edition (ECMA-262) Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

Contributors to this page: evilpie, Sheppy, Marcoos, fscholz, ethertank, fred.wang, Mgjbot, Maian, Dria, Kyodev
Last updated by: fscholz,