Classification:

The range of a injective function is its corresponding range. That is to say, for any y in the corresponding domain of the mapping f, there is at least one x that satisfies y=f(x).

A bijection function is both injective and injective. Also called one-to-one correspondence. Bijective function is often used to indicate that sets X and Y are equipotential, that is, they have the same cardinality. If two sets can establish a one-to-one correspondence, they are said to be equipotential.

Element:

The set x of input values is called the domain of f; The set y of possible output values is called the range of f. The range of a function refers to the set of actual output values obtained by mapping f to all elements in the definition field. Note that it is incorrect to call the corresponding domain, and the function's domain is a subset of the corresponding domain.

In computer science, the data types of parameters and return values determine the definition domain and corresponding domain of subroutines respectively. Therefore, the domain and the corresponding domain are mandatory constraints determined at the beginning of the function. On the other hand, the scope is related to the actual implementation.