MathJax.Hub.Config({ tex2jax: { inlineMath: [['$','$'], ['\\(','\\)']], displayMath: [['$$','$$'], ['\\[','\\]']] }}); $\DeclareMathOperator{\Var}{Var}$ $\DeclareMathOperator{\Cov}{Cov}$ $\DeclareMathOperator{\Span}{Span}$ Notation from book: $F$ means $\mathbb{R}$ or $\mathbb{C}$. You should think it means the real numbers when you read it. I will write all of these notes using $F=\mathbb{R}$, but you could use $\mathbb{C}$ just the same. $V$ is always a vector space over $F$. Linear combination of $m$ vectors $v_1, \ldots, v_m$ is a vector of the form