I like to use $:=$ for "is defined to be equal to", but this is never typeset with the symmetry one would like, as the colon is always too low relatively to the equals sign. Is there any way of getting this to appear correctly?
[Tex/LaTex] How to typeset $:=$ correctly
math-moderelation-symbolssymbols
Related Solutions
For the second question: I haven't checked out the alternatives, but nomencl is what I've had experience with for making a list of symbols.
\newcommand{\Vs}[1]{\FZ{V_{\mathrm{s}#1}}}
\makenomenclature
somewhere in the preamble, plus something like
In some subspace $\Vs{1}$, something happens.\nomenclature{$\Vs{1}$}{A special subspace}
in the main body.
Use an editor or other tool (latexmk, make, etc.) that will automatically run the makeindex command for you, too. On TeXnicCenter with TeX Live 2010, we made a copy of the LaTeX => PDF build profile called LaTeX => PDF (Nomenclature) that runs makeindex each time, and uses the arguments "%tm".nlo -s nomencl.ist -o "%tm".nls. We don't normally use makeindex for anything but nomenclatures, though.
I recommend using a vertically centered colon which matches the equal sign better, such as \vcentcolon from the mathtools package. You can also change it generally to vertical by \mathtoolsset{centercolon}.
Compare standard :=
to the vertically centered:
So your definition could become
\usepackage{mathtools}
\newcommand{\defeq}{\vcentcolon=}
\newcommand{\eqdef}{=\vcentcolon}
with tighter spacing. And since both symbols are already relation symbols, as egreg said, we even could omit \mathrel.
And you could do that even easier by mathtools provided commands:
\documentclass{article}
\usepackage{mathtools}
\begin{document}
$a\coloneqq b \qquad b\eqqcolon a$
\end{document}
Best Answer
See the
mathtoolspackage, which offers the macro\coloneqqfor this purpose.yields
Click image or right here to see it at full size (1600×133).
Note that the colon is slightly too low on the left, but vertically centered on the right.