[Tex/LaTex] Equal matrix column width and draw vertical line

amsmathmath-modematricesspacing

I want to write a matrix with equal column widths, plus have a vertical line down the matrix. By using the solutions given here and here, I have

\documentclass{article}
\usepackage{geometry}
\usepackage{amsmath}
\usepackage{graphicx}

% draw vertical line down matrix
\makeatletter
\renewcommand*\env@matrix[1][*\c@MaxMatrixCols c]{%
  \hskip -\arraycolsep
  \let\@ifnextchar\new@ifnextchar
  \array{#1}}
\makeatother

\begin{document}

\resizebox{\linewidth}{!}{%
\begin{equation}
\begin{pmatrix}[cc|cc]
 C1 & Column2 & C3 & C4 \\ \hline
 C5 & C6 & C7 & Column8
\end{pmatrix}$%
\end{equation}
}

\end{document}

The output matrix does not have equal column widths, and I get an error Missing $ inserted. How can I solve this problem?

Best Answer

Notes:

The error Missing $ inserted is because of the single $ sign at \end{pmatrix}$%.
You can use \resizebox{.9\hsize}{!}{% inside the equation (see Scale an equation to fit exact page width).
I used tabularx to define a new columntype C, witch allows you to set the width of a centered entry by using C{<width>}.

Code:

\documentclass{article}
\usepackage{geometry}
\usepackage{amsmath}
\usepackage{graphicx}

% draw vertical line down matrix
\makeatletter
\renewcommand*\env@matrix[1][*\c@MaxMatrixCols c]{%
  \hskip -\arraycolsep
  \let\@ifnextchar\new@ifnextchar
  \array{#1}}
\makeatother

\usepackage{tabularx}
\newcolumntype{C}[1]{>{\hspace{0pt}\centering\arraybackslash}p{#1}}

\begin{document}

\begin{equation}
    \resizebox{.9\hsize}{!}{\ensuremath{
        \begin{pmatrix}[*2{C{15mm}}|*2{C{15mm}}]
            C1 & Column2 & C3 & C4 \\ \hline
            C5 & C6 & C7 & Column8
        \end{pmatrix}%
    }}
\end{equation}

\end{document}

Result:

Notes:

This does require two runs. First one to determine the locations, and the second to do the drawing.

References:

\tikzmark is from Adding a large brace next to a body of text.

Code:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}

\newcommand{\tikzmark}[2]{\tikz[overlay,remember picture,baseline] \node [anchor=base] (#1) {$#2$};}

\newcommand{\DrawLine}[3][]{%
  \begin{tikzpicture}[overlay,remember picture]
    \draw[#1] (#2.north) -- (#3.south);
  \end{tikzpicture}
}

\begin{document}
\[
\begin{pmatrix}
  \tikzmark{topA}{a} & \tikzmark{topB}b & {0} \\
  a & b & 0 \\
  a & b & 0 \\
  \tikzmark{bottomA}{c} & \tikzmark{bottomB}d & {1}
\end{pmatrix}
\]
\DrawLine[red, thick, opacity=0.5]{topA}{bottomA}
\end{document}

[Tex/LaTex] vertical dotted line in column vector / amsmath matrix

You can do it like this, provided your main matrix has no unusually big objects (otherwise you can play with the first argument to \dottedcolumn that also accepts decimal numbers).

\documentclass{article}
\usepackage{amsmath}

\newcommand{\dottedcolumn}[3]{%
  \settowidth{\dimen0}{$#1$}
  \settowidth{\dimen2}{$#2$}
  \ifdim\dimen2>\dimen0 \dimen0=\dimen2 \fi
  \begin{pmatrix}\,
    \vcenter{
      \kern.6ex
      \vbox to \dimexpr#1\normalbaselineskip-1.2ex{
        \hbox{$#2$}
    \kern3pt
    \xleaders\vbox{\hbox to \dimen0{\hss.\hss}\vskip4pt}\vfill
    \kern1pt
    \hbox{$#3$}
  }\kern.6ex}\,
  \end{pmatrix}
}

\begin{document}
\begin{equation}
  \begin{pmatrix}
    a_1 & b_1 &     &     &     &\\
    c_2 & a_2 & b_2 &     &     &\\
        & c_3 & a_3 & b_3 &     &\\
        &     & c_4 & a_4 & b_4 &\\
        &     &     & c_5 & a_5 & b_5\\
        &     &     &     & c_6 & a_6
  \end{pmatrix}
  \dottedcolumn{6}{T_1}{T_6}=\dottedcolumn{6}{d_1}{d_6}
\end{equation}
\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] Draw a line through one column of a matrix

Notes:

References:

Code:

[Tex/LaTex] vertical dotted line in column vector / amsmath matrix

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