# Is there a circle symbol?

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

• just as a tip, Wikipedia uses LaTeX style markup for their functions. When your press the edit button you can see :[itex](f\circ f)(x) = f(f(x)) = f^2(x)</math> ;) – Davy Landman Jan 5 '11 at 8:43
• 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

It's \circ:

\documentclass{article}
\usepackage{fixltx2e} % To make $$...$$ robust
\begin{document}
$$f \circ f$$
\end{document}

• @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

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.

• 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