Fear of flying persistent fear or anxiety when they consider flying, as well as during flying. They will avoid flying if they can, and the fear, anxiety, and avoidance cause significant distress and impair their ability to function. Take-off, bad weather, and turbulence appear to be the most anxiety provoking aspects of flying. The most extreme manifestations can include panic attacks or vomiting at the mere sight or mention of an aircraft or air travel. Around 60% of people with fear of flying report having some other anxiety disorder. The causes of flight phobia and the mechanisms by which it is maintained were
Thomae's function Then, necessarily, formula_66 and therefore, Likewise, for all irrational formula_68 and thus, if formula_69 then any choice of (sufficiently small) formula_70 gives Therefore, formula_7 is continuous on formula_73 A natural follow-up question one might ask is if there is a function which is continuous on the rational numbers and discontinuous on the irrational numbers. This turns out to be impossible; the set of discontinuities of any function must be an set. If such a function existed, then the irrationals would be an set. The irrationals would then be the countable union of closed sets formula_90, but since the irrationals do