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]. Examples: :echo asin(0.8) 0.927295 :echo asin(-0.5) -0.523599 Can also be used as a |method|: Compute()->asin() {only available when compiled with the |+float| feature}