Writing big block matrix in double column using IEEEtran class

Question

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.

Answer 1

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{equation}
\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.
\end{equation}
\hrule
\end{document}

Answer 2

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}