LaTeX Guidelines

When using Overleaf, keep a look at this

If there is some red, it means that you made a mistake. Click on it to have additional information! For example, clicking on this specific error we get

It is very useful to know that:

• The problem was a misplaced newline.
• The problem is at line 127

Sometimes Overleaf displays a pdf even if there are errors. This does not mean that everything is fine!

Equations

Basics

There are several ways to write an equation in LaTeX:

• inline equations. Is when you place a single dollar signs at both ends, i.e., $ equation_code $. It should be used only when you need a few maths symbols inside a text. You should not use it to write long equations.
• numbered equations at a new line. Is by far the best way to write an equation

\begin{equation}
equation_code
\end{equation}

• not numbered equations (at new line) (which are usually discouraged). Can be obtained in one of the following:
  • Double dollar sign, i.e., $$ equation_code $$
  • Square breakets sign, i.e., \[ equation_code \]

Practice to avoid: forcing a newline, write an inline equation and then force a newline again, i.e.

\\
$ equation_code $ \\

Use instead:

\begin{equation}
equation_code
\end{equation}

Numbering

Every equation or group of equations should be numbered. It is very handy whenever anyone needs to point out something. This translates to

Use

\begin{equation}
equation_code
\end{equation}

whenever possible.

If you need an equation that lasts more than one line I personally prefer the sub-enviroment aligned to the evironment align in order to keep only one number.

Use

\begin{equation}
\begin{aligned}
equation_code_left_aligned1 & equation_code_right_aligned1 \\
equation_code_left_aligned2 & equation_code_right_aligned2
\end{aligned}
\end{equation}

Instead of

\begin{align}
equation_code_left_aligned1 & equation_code_right_aligned1 \\
equation_code_left_aligned2 & equation_code_right_aligned2
\end{align}

Avoid

\begin{equation}
equation_code_left_aligned1 equation_code_right_aligned1
\end{equation}
\begin{equation}
equation_code_left_aligned2 equation_code_right_aligned2
\end{equation}

Numbering is done automatically. If you need a reference to an equation, don't read the equation number in the pdf and reference it as plain text, as in

\begin{equation}
equation_code
\end{equation}
from Equation (7) we conclude ...

This is a problem: whenever a numbered equation is added before the one you are referencing, the numbering will be shifted. Fixing it by hand would be tedious.

Instead, label the equation with \label{} and call the label whenever you need a reference to the equation with \eqref{}. For example:

\begin{equation}\label{1:finalpoint}
equation_code
\end{equation}
from Equation \eqref{1:finalpoint} we conclude ...

As a best practice, begin all your labels with a chapter/section reference, in this way, you won't risk conflicts when using similar labels in different chapters.

Newlines

LaTeX sometimes might prevent you from going to a new line for many different reasons, and often that will raise an error. It is often the case that you might want to skip two lines instead of just one or to go to a newline after the beginning of a theorem or an exercise. You can use workarounds such as

right:

\begin{env} $ $\\
my exercise
\end{env}

wrong:

\begin{env}\\
my exercise
\end{env}

Google and tex.stackexchange are your friends. For example see Theorem environment - line break after label [duplicate]

Other style tips

There is a difference between the product of the tree variables m, a and x and the symbol used for the maximum, i.e. \max. In the same way, it is a best practice to write \min, \argmax, \log or \cos instead of min, argmax, log or cos.

If the symbol you are trying to use is not a LaTeX command (for example Var, to indicate variance), you can use the command \mathrm, e.g., \mathrm{Var}

It might happen that you put between parenthesis some text that is displayed bigger than the parenthesis themselves (for example you might use \sum or \int or some fractions with \frac{numerator}{denominator}. To have the parenthesis automatically adjust, remember to use \left and \right. For example

(bigtext)

would become

\left (
bigtext
\right )

Example

Can you see the difference between

\begin{equation}
V(k,K,s,z)=max_{c,k'}
[
log(c) + 
\beta \sum_{s'} \sum_{z'}
\pi_{z z' s s'} V(k',K', s', z')
]
\end{equation}

and

\begin{equation}
V(k,K,s,z)=\max_{c,k'}
\left [
\log(c) + 
\beta \sum_{s'} \sum_{z'}
\pi_{z z' s s'} V(k',K', s', z')
\right ]
\end{equation}

?