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I want to collect the most common mistakes, misconceptions, pitfalls, etc that (La)TeX and Friends users make. Please one answer for each mistake, misconception, pitfall, etc.

I am only interested in more technical, objective cases rather than psychological, social, subjective cases.

From this complete infinite list of technical and objective cases, we can have a reference how to teach newbies much better directly or indirectly via writing a good book.

The technical and object cases are, for example, as follows.

  • Beginners sometimes use $\huge E=mc^2$ with the hope they will get a huge formula. It actually does not produce the expected result. The correct way is \huge $E=mc^2$.
  • Beginner sometimes use longtable inside table because they assume longtable is the longer version of tabular which is able to be sandwiched in table.
  • etc.
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Not reading an introduction and package documentation. –  Marc van Dongen Oct 21 '13 at 11:36
Aside from answering questions on this site when I don't have a clue what I'm talking about? –  Jubobs Oct 21 '13 at 12:25
There is a similar Community poll on meta: meta.tex.stackexchange.com/a/1596/2693 –  Alan Munn Oct 21 '13 at 13:21
I don't really see how this can get sensible answers, I voted to close as "too broad". As @AlanMunn says the question on meta is perhaps a more suitable location (although it is not really a meta question about the site either) –  David Carlisle Oct 21 '13 at 13:53
Isn't this a sort of "everyone rant here" question? –  marczellm Oct 22 '13 at 21:28
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39 Answers

Several days ago I taught my students how to plot some functions that are either algebraic or transcendental. As usual I introduced them to PSTricks for the sake of its full support for PostScript language.

All functions are expressed in infix form. Some of my students got confused with the algebraic key. They assumed that this key must be enabled via algebraic=true whenever they plot algebraic functions and set it to false whenever they plot transcendental functions. The code they wrote is more and less as follows.

\def\AlgeFunc{x^2-4} % an example of algebraic function
\def\TransFunc{sin(x)} % an example of transcendental function


Actually the algebraic key was created by PSTricks maintainers to allow users to switch from postfix expression (the default in PSTricks) to the infix one or vice versa by setting this key to either false (default) or true.

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I'm a little late to that party, but ho—that's good… –  Sean Allred Jun 19 at 12:14
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My own take on this question is more about the mistakes beginners make because of us. I made too many shameful mistakes (and still do at times), but with my first private beta, I realised that many beginner mistakes were in fact my beginner LaTeX developer mistakes.

They are still beginner mistakes – but I have a feeling of responsibility for a lot of them.

  1. Not teaching users to first read the documentation. Not teaching users to look at the code if the documentation is unhelpful (code does not bite). I have had someone tell me "I didn't dare to modify your package because I didn't know what I was doing"… well, just back it up somewhere and play, code is not sacred).
  2. Not teaching users to send you the log when they want to report a bug or any other issue, even if they do not understand what the error message means. On that matter, I feel like it is helpful to teach all beginners how to read the most basic errors (command already defined, command not defined, underfull and overfull boxes).
  3. Not writing appropriate documentation files for users (we all boast about "literate programming" and we mostly do a good job at writing docs, but not all of them are perfect). We have some beautiful files, and also some barely-commented "implementation" docs with just an introduction and a list of macros that no beginner would ever understand.
  4. Not teaching users the difference between form and content (as mentioned several times before). But I also mean it literally: whether they want to code something for themselves or whether they are requesting a new feature, they need to determine if it is just a stylistic preference or if there is a general purpose behind it (e.g. do we need a simple command or an option for customisation). There is nothing more stupid than creating a whole system that works really well except it is totally impractical in real life.

I hope it is not off-topic… but thinking back, I would think that most of my own beginner mistakes were also often developer (or documentation-writer) mistakes. We are generally good at writing documentations, but we sometimes have a hard time finding the right words for both beginners and experts.

Most of the beginner mistakes mentioned here are not really in the books… or at least they don't show up as sections, tutorials, etc. It is no wonder beginners first look things up on google. We don't write documentations on debugging what we assume will work (it works in the hands of a TeXnician, not in the hands of someone who does things at random).

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One mistake newbies can make is that of having text (in math mode) that extents outside then range of the document.

For example when trying to define Abstract Data Types with many sorts and constructors,the whole line would go until some of the text is just spilling over to the outside of the margin.

One solution would be to use the landscape or geometry package and choose margins that accommodate the work

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The first error for many TeX newbies is not backslashing figure brackets in formulae, when it should be backslashed. So they get $\min {x, 100 - x}$ or even $min {x, 100 - x}$ instead of $\min \{\, x, 100 - x\,\}$.

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Inconsistent syntax causes confusion

As there is a bit inconsistent syntax between length and counter, some users get confused with whether or not they need \.

They often wrongly type \setcounter{\countername}{<value>} rather than \setcounter{countername}{<value>}


\setlength{lengthname}{<dimen>} rather than \setlength{\lengthname}{<dimen>}.

Who made such an inconsistent syntax?

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Attempting to use \ifeven...\else...\fi that actually does not exist. Note that only \ifodd...\else...\fi is available. Probably Knuth likes odd things.

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Personally I think, it is not to care if a given solution is deprecated. So the nag package, as "old habits die hard" and those are too much widespread all over the web.

Last but not least, not to search tex.stackexchange.com which helped me more than a hundred times so far. It helps to distinguish high value answers from bad code snippets in some boards.

I think anything else has been said, already.

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The mistake I always make, even to this day, is forgetting that newlines have syntactic meaning in LaTeX. I'm so used to using empty lines to delimit my text that I do it automatically, and then end up with ugly text (especially when indentation of the first line is enabled).

The other mistake I always make is forgetting when some command requires arguments, like \array, and then it automatically eats up the first thing after it, leading to the "why isn't it rendering the first element of my matrix?"

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Forgetting to add fontenc package when using accent letters.

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