# What is the common order for variables, constants and numbers in math typesetting? [closed]

I am setting my documents in LaTeX and am satisfied with the appearance of the output. Besides this, I am always in doubt how I have to arrange variables, constants and numbers.

Let's talk about the following example:

\begin{align*}
F &= \frac{\textrm{d}W^{'}_{\textrm{mag}}}{\textrm{d}x} \\
&= -\frac{N^2 I^2 \mu_0 a d}{8e^2}.
\end{align*}


Is there a rule which variable or constant should come first? Is it better to place points (like \cdot) between those variables? Do I order the symbols alphabetically and how do I deal with capital letters?

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## closed as off topic by Caramdir, Andrey Vihrov, Loop Space, Joseph Wright♦Nov 17 '11 at 13:00

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Formulae don't consist of random objects, every variable and constant has a meaning. Arrange them by meaning, too. –  Andrey Vihrov Nov 16 '11 at 19:02
That is indeed true. So you would recommend to order everything in groups like "group of distances", "group of electrical constants", ... Or what would you say to the above example? –  Lukas Nov 16 '11 at 20:04
Is this on-topic? Might be more suitable for math.se or physics.se. –  Caramdir Nov 16 '11 at 20:25
Should I move it? –  Lukas Nov 16 '11 at 20:52
Not about your question, but your code can be improved. First, the prime ' is already a superscript, so just write $W'$. Second, don't use \textrm to get words like mag in math; use \text from the amsmath package, which looks better. Third, rather than writing \textrm{d}, try running \newcommand\dd{\mathrm{d}} (\mathrm is better since it is, after all, math) or, better still, \DeclareMathOperator{\dd}{d} (using amsmath again), and then write \dd W, \dd x, etc. Your papers will look better and be easier to write. –  Ryan Reich Nov 17 '11 at 1:18