> N := 10:
> P := [seq]( ithprime( i ), i = 1 .. N ):
> BinarySearch( P, 12, 1, N ); # recursive version
                                  FAIL

> BinarySearch( P, 13, 1, N ); # recursive version
                                   6

> BinarySearch( Array( P ), 13, 1, N ); # make P into an array
                                   6

> PP := Array( -2 .. 7, P ): # check it works if the array is not 1-based.
> BinarySearch( PP, 13 ); # iterative version
                                   3

> PP[ 3 ];
                                   13