 Function class

A function class is a set whose elements are functions, usually with a common domain of a function and codomain. For example,is a class of constant functions. A function class need not be a vector space: here $f_1+f_1$ has constant value two and lies outside $\mathcal{F}$.

An individual member is a function, or map; the class collects such members. This keeps statements about one transformation distinct from statements about a family of possible transformations.