Like sin(, the result of sinֿ¹( depends on whether the calculator is in Radian or Degree mode. However, unlike sine, the result is in degrees or radians, not the argument. A full rotation around a circle is 2π radians, which is equal to 360°. The conversion of θ=sinֿ¹(n) from radians to degrees is θ*180/π and from degrees to radians is θ*π/180. The sinֿ¹( command also works on lists.
The sinֿ¹( function can be defined for all real and complex numbers; however, the function assumes real values only in the closed interval [-1,1]. Because the trigonometric functions and their inverses in the Z80 calculators are restricted only to real values, the calculator will throw ERR:DOMAIN if the argument is outside of this interval, no matter what the mode setting may be.
Since the function sine itself doesn't have the restrictions that arcsine does, and since arcsine is the inverse of sine, you can use sinֿ¹(sin( to keep a variable within a certain range (most useful on the graph screen). Here is an example for a game like pong. The ball travels between -6 and 6.
You could use a flag like this:
:If 6=abs(X \\ X is the position :-D→D \\ D is the direction :X+D→X \\ new position :Pt-On(-54,X,"=")
An easier way to do this, without needing a flag or even an If statement, is using sinֿ¹(sin(
:X+1→X \\ Note: the calculator is in degree mode :Pt-On(-54,sinֿ¹(sin(15X))/15,"=") \\ 15 is used because sinֿ¹ ranges from [-90,90] and X from [-6,6], so 90/6=15
- ERR:DATA TYPE is thrown if you input a complex value or a matrix.
- ERR:DOMAIN is thrown if you supplied an argument outside the interval [-1,1]