Return the arc sine of {expr} measured in radians, as a Float in the range of [-pi/2, pi/2]. {expr} must evaluate to a Float or a Number in the range [-1, 1]. Returns "nan" if {expr} is outside the range [-1, 1]. Returns 0.0 if {expr} is not a Float or a Number. Examples:

:echo asin(0.8)

    0.927295

:echo asin(-0.5)

    -0.523599

Can also be used as a method:

Compute()->asin()