From The Student Room

TSR Wiki > Study Help > Subjects and Revision > Subject Guides > Mathematics > LaTeX

---

LaTeX (pronounced Latec - the x is actually a chi symbol) is an electronic typesetter used mainly for technical or scientific documents but it can be used for almost any form of publishing.

LaTeX is not a word processor! Instead, LaTeX encourages authors not to worry too much about the appearance of their documents but to concentrate on getting the right content. For example, consider this document:

The purpose is not primarily aesthetics as with a word processor, but correct content.

LaTeX contains features for:

   * Typesetting
   * Control over large documents containing sectioning, cross-references,
 tables and figures.
   * Typesetting of complex mathematical formulas.
   * Advanced typesetting of mathematics with AMS-LaTeX.
   * Automatic generation of bibliographies and indexes.
   * Multi-lingual typesetting.
   * Inclusion of artwork, and process or spot colour.
   * Using PostScript or Metafont fonts.

LaTeX is built in to TSR. It helps enormously getting people to help you out if you format your mathematical queries using this method. Below are some basic commands to get you started:

Using LaTeX on TSR:

TSR currently have two LaTeX packages installed, one called TeXLive and an older one called MimeTeX. In terms of functionality and typographical quality the former is better, and this guide will assume you use TeXLive.

To use LaTeX on the TSR forums, simply enter the LaTeX code into [latex][/latex] tags.

e.g. [latex]x = 5[/latex] gives

Multiplication and division

If you need to use these symbols, use \times and \div respectively.

e.g. [latex]3 \times 5 = 15[/latex] gives , while [tex]4 \div 2 = 2[/tex] gives

Plus or minus

[latex]\pm[/latex] gives

Indices

[latex]x^a[/latex] gives

If the exponent is more than one letter/number long, then you have to use curly brackets (i.e. { and } )

e.g. [latex]x^{10}[/latex] gives

For square roots, you use the \sqrt command.

e.g. [latex]\sqrt 2[/latex] gives

Again, if whatever you want to square root is more than one letter or number, you have to use curly brackets (this is the case throughout LaTeX).

e.g. [latex]\sqrt {b^2-4ac}[/latex] gives

If you want to take the n-th root, use the \sqrt[n] command.

e.g. [latex]\sqrt[3]{1+x^2}[/latex] gives

Equals sign and inequalities

To get an equals sign, you simply use the ordinary = sign.

e.g. [latex]2^4=16[/latex] gives

For 'not equal to', use \not=

e.g. [latex]2^4\not=2[/latex] gives

For less than signs, we use <, and for greater than signs, we use >

e.g. [latex]2^4>15[/latex] gives

For 'less than or equal to' signs, we use \leq, and for 'greater than or equal to' signs we use \geq

e.g. [latex]5x+3 \geq 8[/latex] gives

As with the equals sign, the symbol for 'not less than or equal to', 'not greater than', etc. is just \not followed by the symbol (i.e. >, <, \leq, \geq).

e.g. [latex]5x+3 \not\geq 8[/latex] gives

For 'equivalent to' signs, we use \equiv

e.g. [latex]1+ \cot^2 \equiv \mathrm{cosec}^2[/latex] gives

Fractions

We use \frac{numerator}{denominator}.

e.g. [latex]\frac{1}{2}[/latex] gives

e.g.2 [latex]x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}[/latex] gives

Brackets

To get brackets in LaTeX you simply use the parentheses you're used to using when typing Maths without LaTeX.

e.g. [latex](x+1)^2[/latex] gives

If you've got a huge expression with multiple brackets or roots, fractions, etc., you can get larger brackets, using the \left( and \right) commands.

e.g. [latex]f(x) = 3x^2\left(1+\frac{2x+1}{x^2-2} \right)[/latex] gives (compare with [latex]f(x) = 3x^2(1+\frac{2x+1}{x^2-2})[/latex] which gives

Normal text

When writing within TeX tags, it is assumed that any letters denote variables, and hence are italicised. If you want the letters to be written normally, you could use the \mathrm{} tag.

e.g. [latex]\mathrm{hello}[/latex] gives (compare with [latex]hello[/latex] which gives )

Supscripts and superscripts

Superscripts are exactly the same as indices - we again use the ^ command.

e.g. [latex]\mathrm{Cl}^-[/latex] gives (Note that you could also use the [sup] [/sup] tags instead though.)

For subscripts, we use the _ command.

e.g. [latex]x_1+x_2+x_3 = 5[/latex] gives

Sigma notation

To write sums, we use the \sum command.

e.g. [latex]\sum_{i=1}^n i^2 = \frac{1}{6}n(n+1)(2n+1) [/latex] gives

To make the first and last term appear above and below instead of to the side, use \displaystyle.

e.g. [latex]\displaystyle\sum_{i=1}^n i^2 = \frac{1}{6}n(n+1)(2n+1) [/latex] gives

Differentiation

Again, we use \frac{}{} to write dy/dx.

e.g. [latex]\frac{d}{dx} x^2 = 2x[/tex] gives

For f'(x), simply write it out normally within LaTeX tags.

e.g. [latex]f'(x)[/latex] gives

Integration

For the integral sign, use the \int command.

e.g. [latex]\int 2x \, dx = x^2 + C[/latex] gives

(Note the use of the \, command to create a space between the 2x and the dx. Other ways of creating space include the \; command and the \quad command.)

For indefinite integrals, use the commands for subscripts and superscripts.

e.g. [latex]\int^2_0 2x \, dx = 4[/latex] gives

Again, like with sums, the \displaystyle command makes integrals look nicer:

e.g. [latex]\displaystyle\int^2_0 2x \, dx = 4[/latex] gives

Modulus sign

Use | for the modulus sign.

e.g. [latex]\sqrt{x^2} = |x|[/latex] gives

Factorial

Use the exclamation mark like normal.

e.g. [latex]4! = 24[/latex] gives

n choose r

[latex]^n\mathrm{C}_r[/latex] gives

Or, you can use the \binom command:

[latex]\displaystyle \binom{n}{r}[/latex] gives

You could also, if you wanted, write it as a vector(see below).

Greek Letters

Write \x where x is the written form of the Greek letter (i.e. alpha, beta, gamma, ... , omega).

e.g. [latex]\pi[/latex] gives

e.g. [latex]\theta[/latex] gives

If you want the uppercase Greek letter, write the first letter as a capital.

e.g. [latex]\Delta[/latex] gives

Infinity

\infty e.g [latex]\displaystyle\sum_{i=1}^{\infty} \frac{1}{i^2} = \frac{\pi^2}{6}[/latex] gives

Trigonometry

[latex]\cos \theta[/latex] gives

[latex]\sin \theta[/latex] gives

[latex]\tan \theta[/latex] gives

[latex]\sec \theta[/latex] gives

[latex]\mathrm{cosec} \theta[/latex] gives

Alternatively, [latex]\csc \theta[/latex] gives

[latex]\cot \theta[/latex] gives

For the trig functions exponentiated, use ^ after the trig function and before the \theta (or whatever you're using).

e.g. [latex]\sin^2 \theta + \cos^2 \theta=1[/latex] gives

To write 'degrees', you could use the \circ command.

e.g. [latex]\sin 30^{\circ} = \frac{1}{2}[/latex] gives

Logarithms

Use some of the previous commands.

e.g. [latex]\mathrm{log}_a x^k = k \mathrm{log}_a x[/latex] gives

Dots

[latex]x_1+x_2+\cdots[/latex] gives (i.e. central dots)

[latex]x_1+x_2+\ldots[/latex] gives (i.e. dots at the bottom)

[latex]\cdot[/latex] gives

[latex]\bullet[/latex] gives

Matrices and Vectors

For a bold letter, you could use normal text and make it bold (e.g. [b]i[/b] gives i), or if you wanted to use LaTeX, use the \mathbf{} command.

e.g. [latex]\mathbf{i}[/latex] gives

The \vec{} command can also be useful.

e.g. [latex]\vec{AB}[/latex] gives

To write a vector or a matrix, you could use either of the pairs

• \begin{pmatrix} \end{pmatrix}
• \begin{bmatrix} \end{bmatrix}
• \begin{Bmatrix} \end{Bmatrix}
• \begin{vmatrix} \end{vmatrix}
• \begin{Vmatrix} \end{Vmatrix}
• \begin{matrix} \end{matrix}

which enclose the matrix/vector in ( ), [ ], { }, | |, || || and nothing, respectively. Between these \begin{} and \end{} commands, enter the coefficients of the matrix/vector row by row, separating coefficients on the same row with & and separating rows by \\.

Examples:

[latex]\begin{pmatrix} 1 & 2 & 3 \\4 & 5 & 6 \\7 & 8 & 9 \end{pmatrix}[/latex] gives

[latex]\begin{bmatrix} 1 & 2 & 3 \\4 & 5 & 6 \\7 & 8 & 9 \end{bmatrix}[/latex] gives

[latex]\begin{Bmatrix} 1 & 2 & 3 \\4 & 5 & 6 \\7 & 8 & 9 \end{Bmatrix}[/latex] gives

[latex]\begin{vmatrix} 1 & 2 & 3 \\4 & 5 & 6 \\7 & 8 & 9 \end{vmatrix}[/latex] gives

[latex]\begin{Vmatrix} 1 & 2 & 3 \\4 & 5 & 6 \\7 & 8 & 9 \end{Vmatrix}[/latex] gives

and

[latex]\begin{matrix} 1 & 2 & 3 \\4 & 5 & 6 \\7 & 8 & 9 \end{matrix}[/latex] gives

For vectors, simply write a matrix with only one column:

[latex]\begin{pmatrix} x \\ y \\ z \end{pmatrix}[/latex] gives

Arrays

Sometimes, it could be useful to lay out what you write nicely in a table. For many cases, the \begin{matrix} \end{matrix} commands will suffice for this, but a little more control is offered by the \begin{array} \end{array} commands.

When using this, you need to decide beforehand how many columns you want to have, and include a string of letters, one for each column, enclosed in {} directly after the \begin{array} command. The letters indicate what alignment you want of the entries in that column, l for left, c for centre, and r for right.

e.g.

[latex]\begin{array}{rlc} n & n^2 & n^3 \\ 3 & 9 & 27 \\ 4 & 16 & 64 \\ 11 & 121 & 1331 \end{array}[latex]

gives

You can have horisontal and vertical lines in your table. For a horizontal line, use the \hline command , and for a vertical, put a | in the list of column alignments.

e.g.

[latex]\begin{array}{r|lc} n & n^2 & n^3 \\ \hline 3 & 9 & 27 \\ 4 & 16 & 64 \\ 11 & 121 & 1331 \end{array}[latex]

gives

Proofs

[latex]\Rightarrow[/latex] gives

[latex]\Leftrightarrow[/latex] gives

Logic Symbols

[latex]\forall[/latex] gives

[latex]\land[/latex] gives

[latex]\lor[/latex] gives

[latex]\exists[/latex] gives

Other

[latex]\to[/latex] gives

[latex]\lim_{x\to 0}[/latex] gives