An inverse function is a concept of mathematics. A function will calculate some output , given some input . This is usually written . The inverse function does the reverse. Let's say is the inverse function of , then . Or otherwise put, . An inverse function to is usually called Do not confuse with : the first is a value of an inverse function, the second is reciprocal of a value of a normal function.
Let's take a function over real . Then,
At first, make to . For example, to , It also , so It's inverse function is .
Not all functions have inverse functions: for example, function has none (because , and should give both 1 and -1 when given 1)), but every binary relation has its own inverse relation.
Finding the inverse of a function can be very difficult to do.