question: public static long quantile ( long [ ] values , double quantile ) { if ( values == null ) throw new IllegalArgumentException ( "Values cannot be null." ) ; if ( quantile < 0.0 || quantile > 1.0 ) throw new IllegalArgumentException ( "Quantile must be between 0.0 and 1.0" ) ; long [ ] copy = new long [ values . length ] ; System . arraycopy ( values , 0 , copy , 0 , copy . length ) ; Arrays . sort ( copy ) ; int index = ( int ) ( copy . length * quantile ) ; return copy [ index ] ; }
target:  Compute the requested quantile of the given array