# Making size of a 4x4 matrix that consist only 2 parameter of 2x2 matrix to be same size as 4x4 matrix

From the picture below, both are supposed to be 4x4 matrices, but I want to express the first one with 2x2 matrix within 2x2 matrix where the J1 and J2 are 2x2 matrices while the 0 is 2x2 zero matrix. I wanted to make the size to look the same as this looks somehow ugly. Anyone has idea? I attached the code as well.

\begin{multicols}{2}
\begin{enumerate}
\item $\begin{Bmatrix} J_1 & 0 \\ 0 & J_2 \end{Bmatrix}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 0 \\ 0 & 0 & 0 & \lambda_1 \end{Bmatrix}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 1 \\ 0 & 0 & 0 & \lambda_0 \end{Bmatrix}$
\item $\begin{Bmatrix} \alpha & \beta & 1 & 0 \\ -\beta & \alpha & 0 & 1 \\ 0 & 0 & \alpha & \beta \\ 0 & 0 & -\beta & \alpha \end{Bmatrix}$
\end{enumerate}
\end{multicols}


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Please post your code as text not an image, preferably as a complete small document, so people can test their answers. – David Carlisle Mar 13 '14 at 17:09
Can you teach me how to post it as code? >.< – superhuman1314 Mar 13 '14 at 17:11
Just cut and paste the text in to the question, then highlight it and click the {} button in the editor (which just indents it by 4 spaces) the wiki then formats it as a scrollable text box – David Carlisle Mar 13 '14 at 17:12
done, thanks @DavidCarlisle – superhuman1314 Mar 13 '14 at 17:14
Better would be to have a full document \documentclas.... so we don't have to guess where Bmatrix is defined. (I can guess but you never know) (I guessed wrongly about a cases environemnt today when someone didn't show their preamble and I assumed it was amsmath) – David Carlisle Mar 13 '14 at 17:16

\documentclass{article}
\usepackage{multicol,amsmath}

\begin{document}
\begin{multicols}{2}
\begin{enumerate}
\item $\begin{Bmatrix} \begin{picture}(0,0)\put(5,-8){\boldmath\large$J_1 $}\end{picture} && \begin{picture}(0,0)\put(5,-8){\boldmath\large$0$}\end{picture} &\\ \phantom{\lambda_1}& \phantom{\lambda_1}& \phantom{\lambda_1}& \phantom{\lambda_1}\\ \begin{picture}(0,0)\put(5,-8){\boldmath\large$0$}\end{picture} && \begin{picture}(0,0)\put(5,-8){\boldmath\large$J_2 $}\end{picture} &\\ \phantom{0} \end{Bmatrix}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 0 \\ 0 & 0 & 0 & \lambda_1 \end{Bmatrix}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 1 \\ 0 & 0 & 0 & \lambda_0 \end{Bmatrix}$
\item $\begin{Bmatrix} \alpha & \beta & 1 & 0 \\ -\beta & \alpha & 0 & 1 \\ 0 & 0 & \alpha & \beta \\ 0 & 0 & -\beta & \alpha \end{Bmatrix}$
\end{enumerate}
\end{multicols}
\end{document}

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Here is an option that just moves the 2x2 entries into a 4x4 position with an \fbox around them:

\documentclass{article}

\usepackage{amsmath,multicol}% http://ctan.org/pkg/{amsmath,multicol}

\newcommand{\pl}{\phantom{\lambda_0}}
\makeatletter
\newcommand{\twotofour}[2][]{%
\settowidth{\dimen@}{#1}%
\ifdim\dimen@=\z@\settowidth{\dimen@}{#2}\fi%
\makebox[0pt]{%
\smash{\raisebox{.5\normalbaselineskip}{%
\setlength{\fboxsep}{2\fboxsep}%
\fbox{\makebox[\dimen@]{\vphantom{#1}#2}}}\hspace*{4\arraycolsep}}}}
\makeatother
\begin{document}

\begin{multicols}{2}
\begin{enumerate}
\item $\begin{Bmatrix} \pl & \pl & \pl & \pl \\ & \twotofour{$J_1$} & & \twotofour[$J_1$]{0} \\ & & & \\ & \twotofour[$J_1$]{0} & & \twotofour{$J_2$} \end{Bmatrix}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 0 \\ 0 & 0 & 0 & \lambda_1 \end{Bmatrix}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 1 \\ 0 & 0 & 0 & \lambda_0 \end{Bmatrix}$
\item $\begin{Bmatrix} \alpha & \beta & 1 & 0 \\ -\beta & \alpha & 0 & 1 \\ 0 & 0 & \alpha & \beta \\ 0 & 0 & -\beta & \alpha \end{Bmatrix}$
\end{enumerate}
\end{multicols}
\end{document}


Another option with horizontal/vertical rules, defaulting to array for creating the first Bmatrix:

\documentclass{article}
\usepackage{amsmath,multicol}% http://ctan.org/pkg/{amsmath,multicol}
\newcommand{\pl}{\phantom{\lambda_0}}
\makeatletter
\newcommand{\twotofour}[2][]{%
\makebox[0pt]{%
\smash{\raisebox{.5\normalbaselineskip}{%
#2}\hspace*{4\arraycolsep}}}}
\makeatother
\begin{document}

\begin{multicols}{2}
\begin{enumerate}
\item $\left\{\begin{array}{@{}cc|cc@{}} \pl & \pl & \pl & \pl \\ & \twotofour{$J_1$} & & \twotofour[$J_1$]{0} \\ \hline & & & \\ & \twotofour[$J_1$]{0} & & \twotofour{$J_2$} \end{array}\right\}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 0 \\ 0 & 0 & 0 & \lambda_1 \end{Bmatrix}$
\item $\begin{Bmatrix} \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 1 \\ 0 & 0 & 0 & \lambda_0 \end{Bmatrix}$
\item $\begin{Bmatrix} \alpha & \beta & 1 & 0 \\ -\beta & \alpha & 0 & 1 \\ 0 & 0 & \alpha & \beta \\ 0 & 0 & -\beta & \alpha \end{Bmatrix}$
\end{enumerate}
\end{multicols}
\end{document}

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Here I use a TABstack. For the three normal sized ones, the syntax was interchangeable, except for putting the environment contents into the \braceMatrixstack argument. I did need to set up the horizontal intercolumn gap 2ex in advance.

For the large matrix, I just made the letters \LARGE which took care of the vertical requirement. I did need to add a little space to the left and right of the entries, and change the intercolumn gap.

\documentclass{article}
\usepackage{multicol}
\usepackage{tabstackengine}
\begin{document}
\begin{multicols}{2}
\begin{enumerate}
\setstacktabbedgap{3.3ex}
\item $\LARGE\braceMatrixstack{ ~J_1 & 0~ \\ ~0 & J_2~ }$
\setstacktabbedgap{2ex}
\setstackgap{L}{\baselineskip}
\item $\braceMatrixstack{ \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 0 \\ 0 & 0 & 0 & \lambda_1 }$
\item $\braceMatrixstack{ \lambda_0 & 1 & 0 & 0 \\ 0 & \lambda_0 & 1 & 0 \\ 0 & 0 & \lambda_0 & 1 \\ 0 & 0 & 0 & \lambda_0 }$
\item $\braceMatrixstack{ \alpha & \beta & 1 & 0 \\ -\beta & \alpha & 0 & 1 \\ 0 & 0 & \alpha & \beta \\ 0 & 0 & -\beta & \alpha }$
\end{enumerate}
\end{multicols}
\end{document}


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