There is clearly a problem with the "inverses" shown in the table of Examples of Inverse Functions, because many of the functions listed in this table are not one-to-one, and hence are not invertible. For example, , , and so on. To handle this situation, it is customary to restrict the domain of the original function down to a subdomain on which the function is invertible. This subdomain should be large enough that all possible values of the original function are obtained by the function restricted to this subdomain. That is, the range of the function restricted to this subdomain should be the same as the range of the original function. For the function , it is normal to restrict to the interval . These graphs show the function on this restricted domain and its inverse function, :
Notice that the range of the function is , which is the domain of the (restricted) function.
Some authors also use the notation for the arcsin function, and similarly for the other trigonometric functions. This notation is more in keeping with the generic notation. It is important to remember that , not .