# How to fit long equation in single column?

I am writing a two column document. I am trying to fit following equation in one column.

I read following thread and tried to fit my equation to the given solution but it didn't work

Aligned equations in LaTeX

\documentclass[conference]{IEEEtran}
\usepackage{amsmath,graphicx,amssymb,mathtools,mathdots,bm,fixltx2e}
\usepackage[ansinew]{inputenc}

\begin{align*}
\mathbf{x}^{(m,n)}_{ITI}&= \left[xxxxx \cdots xxxxx xxxxx  \cdots  \\
&  \hphantom{{}=1 }  xxxxx \right]^T  \notag\\
\end{align*}

\end{document}


%-----------error--------------------

! Extra }, or forgotten \right.
<template> }
\$}\ifmeasuring@ \savefieldlength@ \fi \set@field \hfil \endtempl...
l.68 \end{align*}

%-------------------------------------

• Welcome to TeX.SX! Your example misses desparately a \begin{document} – user31729 Sep 15 '14 at 15:16
• It's the usual problem: you can't have \left in one alignment cell and the matching \right in another. Just omit them, they serve no purpose in this case. When larger fences are needed, use \bigl, \Bigl, \biggl or \Biggl for the opening and \bigr, \Bigr, \biggr or \Biggr for the closing. – egreg Sep 15 '14 at 15:18
• Well, there is the trick \right]., but it's not nice ;-) – user31729 Sep 15 '14 at 15:20

You can break such an equation while keeping alignment points with a code borrowed from mathtools. I define a \rowvect command that can have as an optional argument \big, \Big, &c.. The optional argument inserts a pair of \bigl…\bigr and the like. It also defines a starred version that inserts a pair of \left…\right.

Demoboth with the classical trick (\left./\right.) and the new command, in which I also propose another alignment:

\documentclass[conference]{IEEEtran}
\usepackage[utf8]{inputenc}
\usepackage{mathtools,graphicx,amssymb,mathtools,mathdots,bm,fixltx2e}

\newcommand\MTkillspecial[1]{% helper macro
\bgroup
\catcode‘\&=9
\let\\\relax%
\scantokens{#1}%
\egroup
}
\DeclarePairedDelimiter\rowvect[]
\reDeclarePairedDelimiterInnerWrapper\abs{star}{
\mathopen{#1\vphantom{\MTkillspecial{#2}}\kern-\nulldelimiterspace\right.}
#2
\mathclose{\left.\kern-\nulldelimiterspace\vphantom{\MTkillspecial{#2}}#3}}

\begin{document}

\begin{align*}
\mathbf{x}^{(m,n)}_{ITI}&=\!\begin{multlined}[t]\left[xxxxx ⋯ xxxxx xxxxx ⋯ \right. \\
\left. xxxxx \right] ^T\end{multlined} \\
\mathbf{x}^{(m,n)}_{ITI}&= \!\begin{multlined}[t]\rowvect[\Big]{xxxxx ⋯ xxxxx xxxxx ⋯ \\[-1.5ex] xxxxx}^T\end{multlined} \\
\mathbf{x}^{(m,n)}_{ITI}&= \rowvect[\Big]{xxxxx ⋯ xxxxx xxxxx ⋯ \\[-1.5ex] & \hphantom{{}=1 } xxxxx}^T\
\end{align*}

\end{document}