# An Unreported Mistake in "Advanced Calculus"

Two weeks ago, I found a mistake in the book that wasn’t in the error list. In p. 430, ln. -3, the ‘<’ sign should actually be a ‘≤’, since it’s given that $\norm{\vect{B} - \vect{A}} \le c / 2$.
P.S. I need to escape the \ inside an inline equation so as to get the norm displayed. A blog post contains a macro for the norm. Another one claims that the $\rm \LaTeX$ code surrounded with double dollar sign (i.e. $$) will be interpreted as an inline equation, but not a displayed one. For example, $$\sum_{i=1}^{n} i = n (n + 1) / 2 will give you $\sum_{i=1}^{n} i = n (n + 1) / 2$.