# LaTeX for Computing Students

Published on theAbout a month ago, I finished my first year at Imperial, reading Computing. Throughout the year, I’ve used LaTeX to write up my notes, solutions to maths assignments and group project reports. Here are a few things I’ve found useful as a Computing student to get the most out of LaTeX.

## Typesetting Code

To typeset code in LaTeX, I use the package `minted`

which provides syntax highlighting. This package uses a program called Pygments, which is written in Python. Having installed Python, Pygments can be installed using pip:

After that, you can use it as follows:

The argument to `minted`

specifies the language. You can see the full list of supported languages on Pygments’ website. It is quite extensive. To compile the LaTeX document with `pdflatex`

, you have to use the flag `--shell-escape`

which allows the LaTeX source code to call shell commands.

To typeset code inline i.e. within a block of text, I use the `\texttt`

command e.g. `\texttt{print("Hi")}`

.

## Typesetting Trees

There were a number of instances, where I needed to draw a tree. This can be done quite easily with the `qtree`

package. To draw a tree with a root node “A”, and child nodes “B” and “C”, write the following:

The square brackets and dot indicate that A is a node with children. To give B a child D:

There is also another package called `tikz-qtree`

that I use to typeset trees. This has the same basic syntax as `qtree`

, but lets you give the arcs labels. For instance going back to our example with the tree with a root node “A” and two children “B” and “C”, to give the arcs between “A” and its children labels:

The `auto`

property controls whether the arc is left or right of the label.

## Typesetting Algorithm Pseudocode

Normally, I write up algorithms using pseudocode, rather than use a particular programming language, so I can abstract away the irrelevant details. To do this I use the `clrscode3e`

package, which was made for the book *Introduction to Algorithms* often known as CLRS. A simple function might be written as follows:

```
\begin{codebox}
\Procname{$\proc{Heapsort}(A)$}
\li \While $\id{size} \neq 0$ \Do
\li $\proc{Swap}(A, 0, \id{size})$
\li $\id{size} = \id{size} - 1$
\li $\proc{Fix-Max-Heap}(A)$
\End
\end{codebox}
```

The pseudocode is contained within a `codebox`

. `\proc`

is a nice way of typesetting function names, and `\id`

is a nice way of typesetting identifiers. Both can only be used in maths mode. This is why when defining the function name using `\Procname`

, I had to put the dollars. `\li`

indicates a line of code. `\Do`

causes the level of indentation to increase. `\End`

causes the level of indentation to decrease. The actual lines and indentation in the LaTeX source code do not affect the presentation.

Other things to note:

- There are special commands defined for keywords such as
`\If`

and`\While`

. - There is a command
`\const`

for constants, e.g.`\const{true}`

. - There is a command for attributes e.g.
`\attrib{s}{length}`

, which means you don’t need`\id`

. - You can make your own keywords e.g.
`\kw{break}`

.

The package automatically adds line numbers. The great thing is that since you have access to maths mode, you can incorporate the necessary mathematical notation in your pseudocode.

## Typesetting Proofs

When doing courses such as Logic, it was necessary to write proofs using a formal proof system such as natural deduction. For these proofs I used the `logicproof`

package. Here is a simple example:

```
\begin{logicproof}{1}
\begin{subproof}
A & ass \\
B & somehow
\end{subproof}
A \to B & $\to I(1, 2)$
\end{logicproof}
```

The numeric argument indicates how deep the nested proofs go. In this case, only 1 level of depth. Nested proofs have a box drawn around them, and are created using the `subproof`

environment. A new proof line is created using `\\`

. This isn’t needed after the last line. The `&`

is used to separate the formula and the description of how the formula was reached. The part for the formula before the ampersand is already in maths mode.

The `logicproof`

package is for Fitch-style proofs, which use boxes. There is an alternative package `bussproofs`

for tree proofs, but I found `logicproof`

far easier to use.

## Other Things

Some other randon things, I’ve found useful:

- The
`physics`

package has an`\abs`

command, for the absolute value. - The
`hyperref`

package means the items in table of contents link to the corresponding pages in the outputted PDF. It also lets you link to websites. - The
`fancyhdr`

package lets you control the headers and footers. - The
`multirow`

package can be used when making tables with the`tabular`

environment. It lets you have a cell that spans multiple rows or multiple columns. - I find it very useful to have macros for the floor and the ceiling function, so I can do
`\floor{x}`

: