\section{Math font styles}			% file "appendix.tex"


Several extra font styles are available in math mode,
since there are so many typographical conventions
in various branches of mathematics.\footnote{By
the way, this is an appendix!}

In set theory (among other fields) one often uses
\emph{calligraphic} letters, e.g.,
\verb9$\mathcal{A}$9; \\
$$ \mathcal{A} ~ \mathcal{B} ~ \mathcal{C} ~ \mathcal{D} ~
\mathcal{E} ~ \mathcal{F} ~ \mathcal{G} ~ \mathcal{R} ~
\mathcal{S} ~ \mathcal{T} ~ \mathcal{Z} $$

In number theory, various number sets are often
indicated using
\emph{blackboard capital} letters, e.g.,
\verb9$\mathbb{R}$9; \\
$$ \mathbb{N} ~ \mathbb{Z} ~ \mathbb{Z}_{17} ~
	~ \mathbb{R} ~ \mathbb{C} $$

Another style used now and then is
\emph{Fraktur} font letters, e.g.,
\verb9$\mathfrak{F}$9; \\
$$ \mathfrak{A} ~ \mathfrak{B} ~ \mathfrak{C} ~ \mathfrak{D} ~
\mathfrak{E} ~ \mathfrak{F} ~ \mathfrak{G} ~ \mathfrak{R} ~
\mathfrak{S} ~ \mathfrak{T} ~ \mathfrak{Z} $$

In vector algebra it is common to use \emph{boldface} letters
to indicate nonscalar values (vectors and matrices), e.g.,
\verb9$\mathbf{A}$9; \\
$$ \mathbf{A} ~ \mathbf{B} ~ \mathbf{C} ~ \mathbf{M} ~
\mathbf{v} ~ \mathbf{x} ~ \mathbf{y} ~ \mathbf{z} $$

One can get \emph{bold italic} letters for vector variables
by using, e.g.,
\verb9$\textbf{\em x}$9; \\
$$ \textbf{\em A B C D E F G s t u v w x y z} $$