100

Is there a circle symbol for the composition of two functions? Or do I have to resort to using other ways to represent that?

  • 38
    just as a tip, Wikipedia uses LaTeX style markup for their functions. When your press the edit button you can see :<math>(f\circ f)(x) = f(f(x)) = f^2(x)</math> ;) – Davy Landman Jan 5 '11 at 8:43
  • 1
    Just for reference, there is also a filled circle in math mode: $\bullet$. – Christian Herenz Aug 31 '18 at 14:00
  • Thanks @ChristianHerenz! The filled circle was exactly what I was looking for. – paldepind Sep 9 '18 at 13:15
136

It's \circ:

\documentclass{article}
\usepackage{fixltx2e} % To make \( ... \) robust
\begin{document}
\( f \circ f \)
\end{document}
  • 24
    @wrongusername. Yes, but it's generally considered a good idea to post something compilable. This one was not exactly hard :-) – Joseph Wright Jan 5 '11 at 8:25
57

Probably this is a good chance to recall the Detexify website, where you can simply draw the symbol you want, and obtain the needed code.

I'm a bad illustrator, but for me, after drawing the circle, \circ was the first hit.

  • 4
    I'd like to add that I tried to find this symbol with detexify but I failed as I found many other similar looking symbols but not \circ. I actually needed to google "latex combine function symbol", to find this question. – ohcibi May 15 '16 at 17:40
  • Would be great if detexify could use context, so you could draw f o g. – OJFord Feb 26 '17 at 4:27

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