# 3.5.1.2.12 Asin

## Description

The asin(x) function returns the inverse of the corresponding trigonometric function. x must be within -1 and 1 for asin , or a missing value is returned. Returned values are in radians, degrees or gradians, depending upon the system.math.angularunits object property (which can also be set in the Options dialog box).

## Syntax

double asin(double x)

## Parameter

x

must be in [-1,1].

## Return

Returns the arcsine of x.

## Example

aa = asin(0.5);
aa = ; //should return 0.5235987755983