Do we have an equation editing HOWTO?

I see other posters writing beautiful integrals and quotients within quotients and matrices and sigma summations and and and... is there a guide for that?

$$\mathfrak{G}_f =\sum_{i = 1}^{n}\begin{vmatrix} a_{i} & \int_{0}^{i}f(t) dt\\ c_{i} & b_{i} \end{vmatrix}$$

YEAH! You need to select "inline" for it to work properly. Changing the accepted answer now.

Seeing as this is the featured FAQ post about entering mathematical notation on this site, I feel it's useful to consolidate here the links to some more useful $$\LaTeX$$ resources that have been pointed out in another question.

neutriNote (last updated: Dec. 20, 2017) - Android APP for note taking. Includes speech-to-text and OCR of $$\LaTeX$$. Free at the Google Play Store. https://play.google.com/store/apps/details?id=com.appmindlab.nano

Feel free to add any others that may be useful to users new to $$\LaTeX$$.

Update: This answer isn't very helpful. Don't let the accepted status or vote count fool you. See Rahul's answer or MathJax basic tutorial and quick reference.

(Viewing source became more straightforward for those with under 2000 points some time ago, as pointed out in a comment. Just click "edit" or "improve this question". The revision history is still useful for other things, but largely irrelevant here.)

Below is the old answer in tinier typesetting.

Expanding on Arturo's last point, you can view the source of any post on the site, regardless of whether or not you have enough rep or are even logged in. You just need the post number. If the post number is XXXXX, then you can go to https://math.stackexchange.com/posts/XXXXX/revisions where there is a link "view source". The post number of a question appears in the URL of the question. To get the post number of an answer, you can use the "link" link in the bottom left of the post, where the post number is at the end of the URL. For example, here are a question and an answer that as of now have not been edited: https://math.stackexchange.com/posts/26438/revisions https://math.stackexchange.com/posts/26586/revisions You can do this on meta, too: https://math.meta.stackexchange.com/posts/1776/revisions You can get to the source more directly by clicking "edit" in the bottom left if logged in, and if a post has been edited then you can click on the time to the right of "edited" in the bottom center of the post. Without having to go to the revision history, you can look at any MathJax source by right-clicking on the math and then clicking "Show Source". All it leaves out is the dollar signs.

• Things changed... nowadays everyone can get to the source more directly, by clicking edit under the post (or improve this question, if not logged in). It's also a bit unfortunate that the users arriving here from help center get a technical point about viewing sources as the top answer (I know you did not upvote and accept it yourself :)... Rahul's answer down there is more along the lines of what this Q+A was meant to be. – user147263 Aug 20 '14 at 3:56
• @900sit-ups: Right, even at the time it was more of a comment than an answer, but a point that I thought deserved to be more widely known. Even then, it didn't make sense to me that it was accepted. Now it's still useful to know how to get to revision history to see close/reopen/delete/undelete/bounty info, but it's not helpful here. Feel free to edit liberally e.g. to make prominent links to better answers, if you are so inclined. Otherwise perhaps I will someday. – Jonas Meyer Aug 20 '14 at 6:18
• I changed the accepted answer. Only took me 10 years. (Almost to the day.) – JCCyC Mar 18 at 22:21

The equations are typeset using $\LaTeX$; there is a link that says "MathJax Help" when you are editing, which links to Kuhn, Scott, and Andreev's Introduction to LaTeX. Most of the formatting is supported, though every once in a while there are a few things you need to do to get MathJax to work right (like extra \ to act as escape characters, etc).

(You can learn some tricks by looking at how some of those people formatted their formulas; you probably can't do it with other people's posts yet because of your reputation, but you can do it to any posts you make if someone edits and formats them).

Also very helpful is Carol Fisher's Alphabetical List of TEX Commands available in MathJax, which gives examples of all MathJax commands, and has a little MathJax sandbox for experiments.

• That site is now paywalled. – PM 2Ring Jul 6 at 10:15

I think someone had already mentioned WP:MATH somewhere. You can just type WP:MATH in the firefox's English wikipedia search.