When to use upright letters in math mode

Question

what are the conventions when to use upright letters in math mode?

Example:

    \begin{align}
     W_{mag} = \frac{1}{2}LI^2
    \end{align}

should the inductivity and the current be typeset in upright letters (\mathrm)?

Welcome to TeX.SX! While this is an interesting question, it's not really about TeX, but rather about style. — egreg, Aug 02 '15 at 16:17
@egreg Would it be better asked on Maths or Physics SE? (I don't know if this is discipline dependent or not?) — cfr, Aug 02 '15 at 16:19
Possibly Physics.SE, if the topic is physics, but I'm not sure if they accept such questions. Anyway, a subscript should be upright if it is verbal (a word or abbreviation thereof) as opposed to a symbol. — egreg, Aug 02 '15 at 16:20
@egreg: I am not very active on Physics.SE, but I doubt they would accept this question, since it's not about Physics itself, 'only' formatting. Of course, the index quantity should be upright if it's an abbreviation or a word, and just as usual if it's a symbol — , Aug 02 '15 at 17:54
Could Graphic Design SX be an alternative? There should be professional typesetters around that may also have experience with mathematics and physics print media. — Ruben, Aug 02 '15 at 19:15
Sometimes I am just lazy and set \DeclareMathOperator\mag{mag} so I can have $W_\mag$ . (correct me if it is evil) — Symbol 1, Aug 04 '15 at 07:02
Quote from Mathematics into Type: "in mathematics it is often necessary to distinguish between functions and properties, which are printed in roman, and variables, which are printed in italic; in symbolic logic both roman and italic variable are often used.'' — Francis, Dec 20 '15 at 21:38
@Symbol1: this won't work, first \mag is a TEX primitive, second using \mathop with subscript will give some grouping issue so you still have to type W_{\mag}. Might as well do \newcommand{\mag}{\mathrm{mag}}. — Francis, Dec 20 '15 at 21:52

score 1 · Answer 1 · edited Apr 13 '17 at 12:35

1

I would typeset this as

\[
    W_\mathrm{mag} = \frac{1}{2} L I^2
\]

i.e. variables should be in standard math mode italic, while subscripts that are simply labels should be upright.

There is no correct answer for this, as it depends on the style of your region, your academic field, and personal taste. See What's the proper way to typeset a differential operator? for a helpful discussion of this topic.

edited Apr 13 '17 at 12:35

Community

1

answered Dec 20 '15 at 21:02

Håkon Marthinsen

1,132

Some tend to also make units upright - which may be helpful for e.g. distinguishing between a volume and volts or an area and amperes. – FelixJN Jun 17 '21 at 10:35

When to use upright letters in math mode

1 Answers1