# centered text/equations inside align environment

is there a way to insert a centered line of text or mathematics inside an align-environment?

For example, in the code below, I'd like to have the \vdots between the equations above and below horizontally centered, completely ignoring the alignment markers:

\documentclass{article}
\begin{document}
\begin{align}
f(1) &= 1 \\
f(2) &= 2 \\
\vdots & \\
f(n) &= n f(n-1)
\end{align}
\end{document}

• Welcome to TeX.SX! Please make your code compilable (if possible), or at least complete it with \documentclass{...}, the required \usepackage's, \begin{document}, and \end{document}. That may seem tedious to you, but think of the extra work it represents for TeX.SX users willing to give you a hand. Help them help you: remove that one hurdle between you and a solution to your problem. – jub0bs Aug 15 '14 at 7:01

Like this?

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\noindent X\hrulefill X
\begin{align}
f(1) &= 1 \\
f(2) &= 2 \\
\shortintertext{\hfil    \vdots \hfil}
f(n) &= n f(n-1) xxxxxxx
\end{align}
\end{document}


• Sorry, apparently I wasn't clear enough when asking the question (I have edited it and added more details). What I want are vdots which are centered independently from all the alignment markers and the content which is above and below. With vdotswithin you have to choose a center point which depends on the alignment markers. – r_faszanatas Aug 15 '14 at 6:47
• @r_faszanatas centered with respect to what? the text width? – user11232 Aug 15 '14 at 6:52
• @r_faszanatas Is it like the updated one? If not, I will delete this :-) – user11232 Aug 15 '14 at 7:05
• That's what I was looking for, thank you very much! – r_faszanatas Aug 15 '14 at 7:15
• @LucasSoares It is defined by mathtools. This leaves little tight vertical space compared to \intertext (which is defined by amsmath). – user11232 May 11 '15 at 16:36

The “official” way of doing this is

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{align}
f(1) &= 1 \\
f(2) &= 2 \\
&\vdotswithin{=} \nonumber \\
f(n) &= n f(n-1) xxxxxxx
\end{align}
\end{document}


But this doesn't answer the question, though. So… why would you like \vdots that ignore the content of align in a “text” line?

• I'm well aware of the "official" way but in my case it was visually unappealing. I have a long chain of aligned equations $f(k)= ...$, just like in your example above, where the right hand side is very long and takes up about 90% of the column width. Vdots under the equal sign just don't look good to me in this case. An example for a centered text line would be something like \intertext{- using our convention that ... -}, which looks better centered than left justified. Again, "better" is of course highly subjective. – r_faszanatas Aug 15 '14 at 7:51