# Problem with big equations (matrices)

I have used LaTeX for writing my paper. The template of journal is in two columns and I have some problems with breaking large equations (especially matrices). Would you please guide me?

Details: I have used the multiline environment but the brackets related to matrix is small.

In another attempt I used equation environment but \\ does not work to go from the upper side of matrix to the lower part of the matrix.

I have written the equation in two structures:

1:

$$\label{eq:eq10} \left[ \begin{matrix} {\bar A}{x_1} + {\tilde B}{x_2} + {\hat C}{x_3} & {P{{\bar A}_{1i}}} & \cdots \\ * & { - (1 - {\mu _1}){P_1}} & \cdots \\ \vdots & \vdots & \ddots \\ * & * & \cdots \\ * & * & \cdots \\ * & * & \cdots \end{matrix} \\ \qquad \qquad \begin{matrix} {P{{\bar A}_{si}}} & {P{{\bar B}_i}} & {{{\bar C}^T}} \\ 0 & 0 & 0 \\ \vdots & \vdots & \vdots \\ { - (1 - {\mu _s}){P_s}} & 0 & 0 \\ * &{ - {\gamma ^2}I} & {{{\bar D}^T}} \\ * & * & { - I} \end{matrix} \right] < 0$$


This solution has the problem that \\ after first \end{matrix} does not work. I mean it does not force the remaining of the equation to go to the next line.

2:

\begin{multline}
\Bigg[
%\left(
\begin{matrix} {\bar A}{x_1} + {\tilde B}{x_2} + {\hat C}{x_3} & {P{{\bar A}_{1i}}} & \cdots \\
* & { - (1 - {\mu _1}){P_1}} & \cdots \\
\vdots & \vdots & \ddots \\
* & * & \cdots \\
* & * & \cdots \\
* & * & \cdots
\end{matrix} \\
%\right
%\left
\begin{matrix} {P{{\bar A}_{si}}} & {P{{\bar B}_i}} & {{{\bar C}^T}} \\
0 & 0 & 0 \\
\vdots & \vdots & \vdots \\
{ - (1 - {\mu _s}){P_s}} & 0 & 0 \\
* &{ - {\gamma ^2}I} & {{{\bar D}^T}} \\
* & * & { - I} \end{matrix}
\Bigg] < 0
%\right)
\end{multline}


This is the second solution. It is well broken in two sub-matrices but it has the problem that the brackets of the matrix are very small for this big matrix, even with the \Bigg command.

How should I fix this problem?

• Welcome to TeX.SX! Please help us to help you and add a minimal working example (MWE) that illustrates your problem. It will be much easier for us to reproduce your situation and find out what the issue is when we see compilable code, starting with \documentclass{...} and ending with \end{document}. – user31729 Sep 30 '14 at 11:15
• You seem to believe that braces are necessary in several places where they aren't: for instance { - (1 - {\mu _s}){P_s}} can and should be typed as -(1 - \mu_s)P_s (with or without spaces, which are ignored). Also it should be \bar{A}, not {\bar A}. Just another example: {P{{\bar B}_i}} is, more simply, P\bar{B}_i. – egreg Sep 30 '14 at 12:00

If amsmath is not forbidden, a solution (rather strange) may be as follows.

\documentclass{article}

\usepackage{amsmath}
\begin{document}

%$$\label{eq:eq10} \begin{gather}\label{eq:eq10} \left[ \begin{matrix} {\bar A}{x_1} + {\tilde B}{x_2} + {\hat C}{x_3} & {P{{\bar A}_{1i}}} & \cdots \\ * & { - (1 - {\mu _1}){P_1}} & \cdots \\ \vdots & \vdots & \ddots \\ * & * & \cdots \\ * & * & \cdots \\ * & * & \cdots \end{matrix} \right. \nonumber\\ \qquad \qquad\left. \begin{matrix} {P{{\bar A}_{si}}} & {P{{\bar B}_i}} & {{{\bar C}^T}} \\ 0 & 0 & 0 \\ \vdots & \vdots & \vdots \\ { - (1 - {\mu _s}){P_s}} & 0 & 0 \\ * &{ - {\gamma ^2}I} & {{{\bar D}^T}} \\ * & * & { - I} \end{matrix} \right] < 0 %$$
\end{gather}

\end{document}


• Why not multline? – egreg Sep 30 '14 at 13:33
• @egreg multline or align or gather... This is a different possibility for OP. – Przemysław Scherwentke Sep 30 '14 at 14:08