The inverse of a function is the same as regular inverse of a relation (functions are relations too). Note that the inverse of a function does not need to be a function. Only injective functions have inverse functions (see inverse of an injection).
The inverse of a function is the same as regular inverse of a relation (functions are relations too). Note that the inverse of a function does not need to be a function. Only injective functions have inverse functions (see inverse of an injection).