math.asin

Returns the arcsine (inverse sine) of num (in radians). This is equivalent to ${\displaystyle \arcsin(x)}$. To convert the output to degrees, you can use math.deg (for example: math.deg(math.asin(0.5))).

Name	arcsine
Lua function	math.asin
Usual notation	${\displaystyle y=\arcsin(x)}$
Definition	${\displaystyle x=\sin(y)}$
Domain of x for real result	${\displaystyle -1\leq x\leq 1}$
Range of usual principal value (radians)	${\displaystyle -{\frac {\pi }{2}}\leq y\leq {\frac {\pi }{2}}}$

ExamplePrint the arcsine of user input
Read a line from the user, print its arcsine in radians, then in degrees.
Code	<nowiki> local num = math.asin(tonumber(read())) print(num) print(math.deg(num)) </nowiki>
Output	Depends on what the user wrote. For instance, if they were to enter 0.5, the numbers printed would be 0.523598776 (${\displaystyle {\frac {\pi }{6}}}$) and 30.

math.asin Function
Syntax math.asin( num : number )
Returns	number
API	math
Source	Lua (source)