best practicesmath-modetext-mode
I am writing an article for an IEEE journal. At one paragraph, I put explanation about a preceding equation like this:
where c1 = 0.0123 is a coefficient from this document.
My question, how should I type it in my latex document? Should I type the math expression this way: $c_{1} = 0.0123$, or can I do it this way: $c_{1}$ = 0.0123, or maybe like this: $c_{1} =$ 0.0123? Please attach some dependable sources if possible.
Don Knuth touched on this topic in his article for TUGboat -- "Typesetting Concrete Mathematics". His examples don't include units (for that, the siunitx package is a good choice, as already mentioned), but the method for determining what is math and what isn't is well illustrated otherwise.
(The article is set in Knuth's Concrete fonts, and shows some of the special techniques used in setting that book. Irrelevant for this question, but interesting nonetheless.)
Your question is very far from clear. Here's a hint:
\documentclass{article}
% This package is just for the example
\usepackage{lipsum}
\newenvironment{braced}
{\par\smallskip\hbox to\columnwidth\bgroup
\hss$\left\{\begin{minipage}{\columnwidth}}
{\end{minipage}\right\}$\hss\egroup\smallskip}
\begin{document}
\lipsum[2]
\begin{braced}
\lipsum[3]
\end{braced}
\lipsum[4]
\end{document}
The environment ends a possible preceding paragraph and inserts a small vertical space. Then it opens an \hbox as wide as the current \columnwidth (you may want to use \linewidth if you plan to use this inside a list environment). In this box math mode is started and \left\{ is issued. Then a minipage is opened, as wide as \columnwidth. This finishes the starting part. The ending part closes the minipage and issues \right\} to balance the left delimiter and closes math mode; then the \hbox is closed and typeset. A small vertical space is added. Since \hss is added at either side of the math formula, the braces will be in the margins (the box is actually wider than \columnwidth, but the shrinkable glue provided by \hss makes it appear to fit).
Best Answer
If
is text then it should be marked up as
If it is math then it should be marked up as
Using half text and half math for the same expression will produce poor spacing and/or inconsistent fonts.
Knuth in his paper cited in the answer to a related question describes an issue where he'd marked up positive numbers as
1and negative numbers as$-1$and then got caught out when changing the document's font setup so that math digits used a different font from text digits which had the unwanted consequence of making negative and positive numbers use different fonts. The strong recommendation is to always use math mode for math, even if it is just a minimal expression such as$1$or$x$.