asin (arc sine function)
The asin function computes the arc sine of its argument; that is the value whose sine is the given argument. The result is in radians and lies between -PI/2 and PI/2 (the range is approximate due to rounding errors).
Null is returned if the argument is not between -1 and 1.
q)asin 0.8 0.9272952
For a complete list of functions, see the kdb+ Function Reference.