## Fussy spacing issues

These are issues that won't affect the correctness of formulas, but might make them look significantly better or worse. Beginners should feel free to ignore this advice; someone else will correct it for them, or more likely nobody will care.

Don't use `\frac`

in exponents or limits of integrals; it looks bad and can be confusing, which is why it is rarely done in professional mathematical typesetting. Write the fraction horizontally, with a slash:

$$\begin{array}{cc}
\mathrm{Bad} & \mathrm{Better} \\
\hline \\
e^{i\frac{\pi}2} \quad e^{\frac{i\pi}2}& e^{i\pi/2} \\
\int_{-\frac\pi2}^\frac\pi2 \sin x\,dx & \int_{-\pi/2}^{\pi/2}\sin x\,dx \\
\end{array}$$

The `|`

symbol has the wrong spacing when it is used as a divider, for example in set comprehensions. Use `\mid`

instead:

$$\begin{array}{cc}
\mathrm{Bad} & \mathrm{Better} \\
\hline \\
\{x|x^2\in\Bbb Z\} & \{x\mid x^2\in\Bbb Z\} \\
\end{array}$$

For double and triple integrals, don't use `\int\int`

or `\int\int\int`

. Instead use the special forms `\iint`

and `\iiint`

:
$$\begin{array}{cc}
\mathrm{Bad} & \mathrm{Better} \\
\hline \\
\int\int_S f(x)\,dy\,dx & \iint_S f(x)\,dy\,dx \\
\int\int\int_V f(x)\,dz\,dy\,dx & \iiint_V f(x)\,dz\,dy\,dx
\end{array}$$

Use `\,`

to insert a thin space before differentials; without this $\TeX$ will mash them together:

$$\begin{array}{cc}
\mathrm{Bad} & \mathrm{Better} \\
\hline \\
\iiint_V f(x)dz dy dx & \iiint_V f(x)\,dz\,dy\,dx
\end{array}$$

This post imported from StackExchange Mathematics Meta at 2014-04-16 16:08 (UCT), posted by SE-user MJD