Sublinear function
（重定向自Sublinear）
A sublinear function (or functional, as is more often used in functional analysis), in linear algebra and related areas of mathematics, is a function 
on a vector space V over F, an ordered field (e.g. the real numbers 
), which satisfies
In functional analysis the name Banach functional is used for sublinear function, especially when formulating Hahn–Banach theorem.