# Writing big block matrix in double column using IEEEtran class

I'm writing a paper in IEEE journal format. I have a BIG matrix as follows:

\begin{align}
\begin{bmatrix}
\begin{pmatrix}
E^\top KA &0 \\
0 &V^\top E^\top U \hat{K} U^\top AV
\end{pmatrix} +
\begin{pmatrix}
A^\top KE &0 \\
0 &V^\top A^\top U \hat{K} U^\top EV
\end{pmatrix}
&\begin{pmatrix}
E^\top KB \\
V^\top E^\top U \hat{K} U^\top B
\end{pmatrix} \\
\begin{pmatrix}
B^\top KE &B^\top U \hat{K}U^\top EV
\end{pmatrix}
&0
\end{bmatrix} + \cr
\begin{bmatrix}
\begin{pmatrix}
C^\top C &-C^\top CV \\
-V^\top C^\top C &V^\top C^\top CV
\end{pmatrix}
&0 \\
0 &-\gamma^2 I
\end{bmatrix} = Q_2 \preceq 0
\end{align}


How can i make it fit in the two column paper format? I am relatively new to LaTeX. Thanks in advance.

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Have a look at the example given in the manual of IEEEtran page 11. –  percusse Jul 14 '12 at 12:44

Given the narrow measure (line width) set by the IEEEtran document class, I believe you have little choice but to break up the entire expression into several parts. One way to do this is to define various submatrices and assign them short names, such as X_1, X_2, etc., and then use these short names in the main expression. For instance, the following might work for you and for the readers of your paper; obviously, you should probably use symbol names that are a bit less generic than X and Y. The \hrule (horizontal rule) commands are there just to indicate the width of the column of text.

\documentclass{IEEEtran}
\usepackage{mathtools}
\begin{document}\pagestyle{empty}
\hrule

\medskip
Let us define
\begin{align*}
X &=
\begin{bmatrix}
E^\top KA & 0 \\
0         & V^\top E^\top U \hat{K} U^\top AV
\end{bmatrix}\,, \\
Y &=
\begin{bmatrix}
E^\top KB \\
V^\top E^\top U \hat{K} U^\top B
\end{bmatrix}\,,\\
\shortintertext{and}
Z &=
\begin{bmatrix}
C^\top C         & -C^\top CV \\
-V^\top C^\top C & V^\top C^\top CV
\end{bmatrix}\,.
\end{align*}
Then
$$\begin{bmatrix} X+X^\top & Y\\ Y^\top & 0 \end{bmatrix} + \begin{bmatrix} Z & 0\\ 0 &-\gamma^2 I \end{bmatrix} = Q_2 \preceq 0.$$
\hrule
\end{document}

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Thanks for your response. I had seen in one paper, that the big matrices are divided into two parts, the upper one consists of first few columns, while the remaining columns are given at the bottom. How can i do that? –  Mohsin Jul 14 '12 at 15:36
@Mohsin -- As I'm sure you know too, there are a great many different ways of displaying components of a large matrix. Could you provide a reference to a specific example you have in mind? –  Mico Jul 14 '12 at 15:38
Indeed!! It was basically a chinese control conference paper... 'Model reduction for uncertain systems using LMIs' by Li Minghao –  Mohsin Jul 14 '12 at 15:55
@Mohsin, since I'm not a member of the IEEE and don't have an easy affiliation with it either, I can't access this paper without paying \$31 up front. Could you maybe edit your posting to include an excerpt from this paper that shows the matrix (or matrices) in question? Assuming you give a proper reference, this shouldn't violate copyright laws. That way, others will also have a shot at providing an answer. :-) –  Mico Jul 14 '12 at 16:29
I can explain it as follows, for example: M = [A B C ...; D E F] This is one complete matrix in which the block A B C are the first three columns, while the D E F are the remaining 3 columns of the matrix M. Here they mention the A,B, C first and then the remaining columns. By the way, know how I include anything from this paper here. I am very new here... –  Mohsin Jul 14 '12 at 16:54

In control papers, it's customary to define in the preliminaries; He{x} := x^t+x for large LMIs especially for Hinf problems. So here you can factor out the output equation part and try to fit it in two lines.

\documentclass{ieeetran}
\usepackage{amsmath}
\usepackage{lipsum} % For dummy text
\author{The author}
\title{The title}
\begin{document}
\maketitle
\begin{abstract}
\lipsum[1]
\end{abstract}
\lipsum[2-5]
\begin{multline}
\textrm{He}\left\{
\begin{bmatrix}
E^\top KA &0                                 &0\\
0         &V^\top E^\top U \hat{K} U^\top AV &0\\
B^\top KE &B^\top U \hat{K}U^\top EV         &0
\end{bmatrix}
\right\} +\\
\begin{bmatrix}
C^\top &0\\
-V^\top C^\top&0\\
0 &\gamma I
\end{bmatrix}
\begin{bmatrix}
C & -CV &0\\
0 & 0  &\gamma I
\end{bmatrix} := Q_2 \preceq 0
\end{multline}
\lipsum[3-5]
\end{document}


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