Algebraic and Analytic Geometry
《Algebraic and Analytic Geometry》 · 第 349 页 · Section 6.2「Gram–Schmidt Orthogonalization Process and Orthogonal Complements」，定义段
Let $S$ be a nonempty subset of an inner product space $V$. We define $S^\perp=\{x\in V:\langle x,y\rangle=0\text{ for all }y\in S\}$; the set $S^\perp$ is called the orthogonal complement of $S$.