| 释义 |
function A function (or mapping) f from S to T, where S and T are non‐empty sets, is a rule that associates with each element s of S (the domain) a unique element f(s) of T (the codomain). s is the argument or input, and f(s) is the image or output. The notation f: S → T, read as “f from S to T”, is used. The subset of T consisting of those elements that are images, that is {f(s) | sεS}, is the image or range of f. If f(s) = t, it is said that f maps s to t, written s↦t. See bijection, graph (of a function), one-to-one mapping, onto mapping, real function, morphism.
|