function binSearch(A,l,n,x)
   m = l+math.floor((n-l)/2)
   if A[m] == x  then
      return m
   elseif n-l < 1 then
      return false
   else
      tmp1 = binSearch(A,l,m,x)
      if not tmp1 == false then
	 return tmp1
      end
      tmp2 = binSearch(A,m+1,n,x)
      if not tmp2 == false then
	 return tmp2
      end
   end
end