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I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?

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I think this should become a community wiki. It's being asked over and over again, for different symbols. And maybe a better title would be 'How to look up any symbol for LaTeX?' –  Count Zero Sep 15 '11 at 14:51
    
@AlanMunn -- asking you since you edited the question ... maybe "extend" the title to "how to look up a symbol or the style of a math alphabet"? many, many questions are about alphabet styles, not just other symbols, and this doesn't seem to be obvious. –  barbara beeton Jun 5 '13 at 12:59
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11 Answers

up vote 317 down vote accepted
  1. You can look things up in the Comprehensive LaTeX symbols list. It can usually be easily accessed with texdoc symbols or texdoc symbols-a4 (in MiKTeX the latter only).

  2. Another good option is to try Detexify, which allows you to draw the symbol and tries to recognize what you've drawn. Here is a screenshot:

    Screenshot

  3. If you are using the package unicode-math, then besides using any Unicode character list, the list of all supported symbols (texdoc unimath-symbols) is very useful as it also lists which symbols are available in the various fonts.

The above techniques provide an adequate way of finding symbols but are not necessarily foolproof since you sometimes need to know what you're looking for in order to find it. For example, in Typing Following notation in Latex it may not be apparent that "vector fields in differential geometry" are somehow related to "bowties". To that end, searching for a symbol rotated 90 degrees or flipped horizontally, say, might lead you in the right direction.

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+1, Detexify was a lifesaver for me, many times! –  Amir Rachum Jul 26 '10 at 19:36
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Yup, Detexify has become the best way to do this –  Joseph Wright Jul 26 '10 at 19:38
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Would you mind to change the link from "this website" to "Detexify"? Nice answer though! –  Nils Schmidt Jul 28 '10 at 22:59
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Detexify is particularly useful if you get it on a device with a touch screen (there are Android/iPhone apps for it) -- personally, I find it rather difficult to draw with my mouse, but finger works fine :) –  TJ Ellis May 31 '11 at 19:49
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It's worth pointing out that the Select from the complete list! link in the results list will display the symbols list ordered by score, so it's more useful than the intimidating term complete list might suggest. –  Jake Oct 21 '11 at 6:25
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Theres lots of ways of doing this, but the two I've found to be most useful are these:

  • Detexify Allows you to draw the symbol, and then guesses based on similar symbols. This is great for me because I don't always remember the name of the symbol, and even if I know the name, I may not have the correct name.

  • AMS LaTeX Short Math Guide This short pdf gives an overview of AMS LaTeX functionality, and includes a pretty thorough list of most of the math symbols (un)commonly used in proofs and formulas.

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+1 for the magic combination of detexify and the AMS guide –  Norman Gray Jul 26 '10 at 20:25
    
Detexify is great, but I wouldn't say that the coverage of the Short Math Guide for LaTeX is representative. –  Lover of Structure Mar 13 '13 at 5:22
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The old school way is to look it up in the Comprehensive LaTeX Symbol List (warning: 4 MB PDF file).

The new hotness is to use DeTeXify which uses handwriting recognition to look the symbol up for you.

DeTeXify even comes in an iPhone/Andriod app- you can get a free version or pay for one. The only difference is that with the paid app you are making a donation to the developer- the feature set is exactly the same.

The author is planning to work on a mobile version of the website that will supplant these apps.

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I often look up the relevant topic on Wikipedia, (e.g. Set theory) and look at the source there. Wikipedia uses LaTeX for math markup as well.

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For uncommon symbols, instead of search documentation on-line or in a big PDF to find packages and commands to include in my code, I have found useful sometimes to compile the whole table of characters of a font (even in the working document) to quickly find, for example, the skull of the omding font that is \char194. Of course, you have first to know that you have a font file with that name (omding.tfm) but then is easy:

\documentclass{article}
\usepackage{fonttable}
\begin{document}
\fonttable{omding}
\font\omding=omding
\omding  \char194
\end{document}

MWE You can also search for a skull the in Comprehensive LaTeX symbols list, or paint a skull in Detexify, or remember the easy command "\skull" (and do not forget load the skull package and enter in math mode) o try to find a \dingbat or \ding{whatever}... but when I want a skull (really never) must be that of white bones (just try the other methods if you don't know what I mean).

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There's also an iPhone app for Detexify, which I've used occasionally, for some reason ...

Links (on the US iTunes App Store): free version and supporter version ($0.99, same functionality).

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This reference has yet to fail me; it has all the symbols typeset along with the \foo command needed to generate them. There's also this PDF, which is considerably better put-together and covers other symbols besides the base math ones

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The LaTeX wikibook Mathematics section has been very helpful for me.

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I've just come across this list http://milde.users.sourceforge.net/LUCR/Math/unimathsymbols.pdf which lists characters using unicode numbers, their representation, and their (La)TeX command, together with other useful information.

Here's a random sample of what it looks like:

symbol list including unicode

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This seems also to be useful: mirror.ctan.org/biblio/biber/documentation/utf8-macro-map.html. –  Speravir Mar 19 at 4:58
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Some utilities for lookup symbols in Unicode:

  • ent2latex: A Perl script to translate Unicode symbols to LaTeX commands. (However, it doesn't utilize math fonts.)

  • kcharset: A KDE application to lookup Unicode. (Well, you can input some symbols in Unicode directly, or lookup the corresponding LaTeX command by ent2latex.)

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I use the Daum Equation editor then just copy and paste the code at the bottom (you can specify Tex,LaTeX, etc.) and even favourite the equations/symbols to avoid having to re-look them up every time you use them. Not sure if they have EVERY symbol, but it has been a good reference for me so far!

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protected by Claudio Fiandrino Jun 21 '13 at 12:04

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