# Typing Mathematics Online

You may wish to enter mathematical expressions in some of your comments on this website, on other websites, or a variety of supported applications. This is often possible if you use a variation of the $$\LaTeX$$ mathematical typesetting commands to enter your equations. For example, to enter the fraction $$\frac{a}{b}$$ you can type

$$\frac{a}{b}$$

$$\LaTeX$$ commands for mathematical expressions are always inserted between starting and ending tags (here they are $$ and $$, respectively). Mathematical expressions can be entered in two different “modes”: inline mode is used for expressions that are the same height as a normal line of text, and display mode is used to create larger expressions that usually appear on a separate line. To enter expressions in display mode, use the tags $ and $ instead.

$$\LaTeX$$ is a very powerful typesetting language, so there’s a lot to learn! Here are a few basic commands.

• Superscripts are entered using ^ and subscripts with _, so $$x^2$$ is entered as x^2. Be careful, though, if you want items to be grouped. Typing x^3y produces $$x^3y$$, not $$x^{3y}$$. To get $$x^{3y}$$ you need to use brace brackets, { and }, to indicate your intended grouping. So, $$x^{3y}$$ is created using x^{3y}.
• Integrals are entered using \int, and the upper and lower limits are entered using ^ and _ respectively. So, \int_0^\infty produces $$\int_0^\infty$$. Similarly, sigma notation is entered using \sum, so \sum_{n=1}^\infty produces $$\sum_{n=1}^\infty$$. Notice that brace brackets were needed here.
• As seen in the first example, fractions are entered using \frac{}{}, with the numerator entered in the first set of brace brackets, and the denominator in the second. So, \frac{1}{n^2} produces $$\frac{1}{n^2}$$.

$$\LaTeX$$ commands for mathematical expressions are supported on a number of different websites, so it’s useful in other places as well. For example, to enter $$\LaTeX$$ in Edmodo use

$…$

$$…$$.

Be careful, though, when you’re entering $$\LaTeX$$ commands between these math tags—$$\LaTeX$$ commands always involve the backslash (\) rather than the forward slash (/)!

If you want to know how to enter any other mathematical symbols or expressions, just let me know in a comment below.

## Installing $$\LaTeX$$ on Your Computer

While there are some online websites that allow you to create $$\LaTeX$$ documents, the best way to start working with $$\LaTeX$$ is to install it on your computer (which then gives you access to the full set of features $$\LaTeX$$ provides).

$$\LaTeX$$ is a typesetting system, and to create and edit $$\LaTeX$$ documents, you’ll need to use a $$\LaTeX$$ editor.

### Mac Installation

If you’re on a Mac, everything you need is included in the MacTeX distribution, which you can download here (with installation instructions included on the linked page). This installation includes the $$\LaTeX$$ editor TeXShop, which is what you’ll use to create your $$\LaTeX$$ documents.

### Windows Installation

If you’re on Windows, you can use the MiKTeX distribution, which you can download here (with installation instructions provided here). This installation contains the $$\LaTeX$$ editor TeXworks, which is what you’ll use to create your $$\LaTeX$$ documents.

### Next Steps

Once you’ve got  $$\LaTeX$$ installed and running, many of your next questions are likely to be answered in this introductory document.

## 5 Replies to “Typing Mathematics Online”

1. Dr. McDonald says:

Here’s a comment that contains some mathematics! $\sum_{n=1}^\infty \frac{1}{n^2}$

The code used to produce this is $\sum_{n=1}^\infty \frac{1}{n^2}$

2. Dr. McDonald says:

If you need to enter a vector equation, something like $\vec{r}=\lambda \begin{pmatrix} 1\\2\\-3\end{pmatrix} +\begin{pmatrix}2\\-2\\1\end{pmatrix}$

The code used to produce this is $\vec{r}=\lambda \begin{pmatrix} 1\\2\\-3\end{pmatrix} +\begin{pmatrix}2\\-2\\1\end{pmatrix}$

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