# 9 LaTeX typesetting errors that will hurt your eyes

Posted by Jason Polak on 18. May 2017 · Write a comment · Categories: math · Tags:

Here are some common LaTeX typesetting errors that you can avoid to make your document look good:

## The wrong inner product

Ever seen inner products written like this?

This horrible inner product typesetting was made using signs that should only be used as relation symbols such as less than or greater than. If you want to typeset a proper inner product using angle brackets, use \langle and \rangle.

## Using multiple fonts

When the ability to use other fonts are discovered, it leads to using them. Unfortunately, sometimes they get mixed when they shouldn’t:

This fragment shows a sans-serif font being used to emphasise a definition word in a sentence that is typeset with a serif font. Truly shocking, though it’s not as bad as using Times New Roman for the body text and Computer Modern Roman for the math font. Now that’s really bad. Take my advice: stick to one font.

## Not using the right-sized parentheses

This is one of the most common mistakes. Ever see something like this:

Yeah. This was acceptable when we were using typewriters. Not any more. For correctly sized parentheses and other delimters, use \left before the left delimiter and \right before the right delimiter.

## Keep weird fraktur letters to a minimum

Ever see a document with hundreds of fraktur letters?

Seriously? What’s wrong with $I$ and $J$?

## Use numbering that makes sense

What about those definitions, theorems, lemmas, and corollaries that all use separate numbering?

This makes for finding stuff in a document frustrating, and impossible in a long one. Use one numbering system to help everyone keep their sanity.

## Don’t use the bullet

What’s a bullet? It’s activated with the \bullet command. It produces the following monstrosity:

It’s those black discs, which should only be used for bullet points. The problem is that a paragraph with a hundred bullets in it looks plain ugly. Find some other way to denote chain complexes.

## Make sure operators are defined

Or else, you’ll get an operator that is typeset in italics:

Operators with multiple characters like Aut to denote automorphisms should be typeset upright, and to do that just use \DeclareMathOperator{\Aut}{Aut} so that you can write \Aut(X) instead of Aut(X). Much better right?

## Greek letters?

Please take a good, hard stare at a bunch of greek letters you should never use:

\digamma: looks too much like the letter F. \varkappa: looks too much like the Russian letter ?. Also, no one could recognize it. \varrho: why not just use the regular rho? \varsigma: definitely looks like a malformed zeta. \Xi: The worst letter imaginable.