Draw vertical line down aligned equation

Question

How do I go about drawing a line vertically down aligned equations like this:

I attempted using a tabular environment but some of the spacing is too much.

This is what I have so far:

CODE

\documentclass[10pt]{book}
\usepackage{amsmath,amssymb,amsfonts} 


\begin{document}
% Table generated by Excel2LaTeX from sheet 'Sheet1'
\begin{table}[htbp]
  \centering
  \caption{Add caption}
    \begin{tabular}{ccc|ll|ll|l|ll|l}
    U1    & =     & \multicolumn{1}{c}{X1} &       & \multicolumn{1}{c}{} &       & \multicolumn{1}{r}{} & \multicolumn{1}{r}{} &       & \multicolumn{1}{r}{} &  \\
    U2    & =     & X2    &       & \multicolumn{1}{c}{} &       & \multicolumn{1}{r}{} & \multicolumn{1}{r}{} &       & \multicolumn{1}{r}{} &  \\
    U3    & =     & X3    & +     & X1    &       & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} &       & \multicolumn{1}{l}{} &  \\
          & =     &       &       &       & +     & X2    & \multicolumn{1}{l}{} &       & \multicolumn{1}{l}{} &  \\
    Un    & =     & Xn    &       &       &       &       & …     & +     & Xn-1  &  \\
    Sn    & =     &       &       &       &       &       &       &       &       & Xn \\
    \end{tabular}%
  \label{tab:addlabel}%
\end{table}%

\end{document}

score 4 · Answer 1 · answered Feb 13 '19 at 16:07

The blkarray package provides a convenient means to produce aligned (and non-aligned) material with separators spanning different rows, inside a maths environment (such as align). This is done by adding 'blocks' with different column specifications to a 'blockarray' environment defined by the package. In the below code, I use one block per row, simply adding an extra column line for each successive row (note that each block must still have the same number of total columns, albeit empty ones):

\documentclass[10pt]{book}
\usepackage{amsmath}
\usepackage{blkarray}
\begin{document}
\begin{align*}
 \begin{blockarray}{cccccc}
  \begin{block}{cccccc}
    U_1=X_1&&&&&\\ % Row 1
  \end{block}
  \begin{block}{c|ccccc}
    U_2=X_1&&&&&\\ % Row 2
  \end{block}
  \begin{block}{c|c|cccc}
    U_3=X_3&+X_1'&&&&\\  % Row 3
  \end{block}
  \begin{block}{c|c|c|ccc}
    &&+X_2'&&&\\ % Row 4
  \end{block}
  \begin{block}{c|c|c|c|cc}
   &&&&&\\ % Row 5
  \end{block}
  \begin{block}{c|c|c|c|c|c}
    U_n=X_n &&&\ldots&+X_{n-1}'&\\ % Row 6
  \end{block}
  \begin{block}{c|c|c|c|c|c}
    s=\phantom{x}&&&&&+X_n'\\ % Row 7
  \end{block}
  \end{blockarray}
\end{align*}
\end{document}

Output:

score 4 · Answer 2 · answered Feb 13 '19 at 16:23

Here is a proposition, with tabularreplaced by array, a smaller value for arraycolsep and some improvements:

\documentclass[10pt]{book}
\usepackage{amsmath,amssymb}
\usepackage{makebox}


\begin{document}

% Table generated by Excel2LaTeX from sheet 'Sheet1'
\begin{table}[htbp]
  \centering \setlength{\arraycolsep}{3pt}
  \caption{Add caption}\[
    \begin{array}{c@{{}={}}c|ll|ll|l|ll|l}
    U_1 & X_1 \\
    U_2 & X_2 & \\
    U_3 & X_3 & + & X_1 \\
    \multicolumn{1}{c}{\makebox*{$U_3$}{ $ \smash[t]{\vdots} $\hspace{1.5em}}} & \smash[t]{\vdots} & & & + & X_2 \\
    U_n & X_n & & & & & \cdots & + & X_{n-1} \\
    S_n & & & & & & & & & X_n \\
    \end{array} \]%
  \label{tab:addlabel}%
\end{table}%

\end{document}

Unrelated: needless to load masfonts when you load amssymb: the latter package already loads it.

Note that the spacing would be slightly different, see math mode - Match spacing of align in array environment - TeX - LaTeX Stack Exchange — user202729, Jun 13 '22 at 00:46

score 2 · Answer 3 · answered Feb 13 '19 at 16:04

Some spacing is too much? Reduce it.

\documentclass[10pt]{book}
\usepackage{amsmath,amssymb,amsfonts} 

\begin{document}
\begin{table}[htbp]
  \centering
  \caption{Add caption}
    \begin{tabular}{c@{\ }c@{}c|l@{\ }l|l@{\ }l|l|l@{\ }l|l}
    U1    & =     & \multicolumn{1}{c}{X1} &       & \multicolumn{1}{c}{} &       & \multicolumn{1}{r}{} & \multicolumn{1}{r}{} &       & \multicolumn{1}{r}{} &  \\
    U2    & =     & X2    &       & \multicolumn{1}{c}{} &       & \multicolumn{1}{r}{} & \multicolumn{1}{r}{} &       & \multicolumn{1}{r}{} &  \\
    U3    & =     & X3    & +     & X1    &       & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} &       & \multicolumn{1}{l}{} &  \\
          & =     &       &       &       & +     & X2    & \multicolumn{1}{l}{} &       & \multicolumn{1}{l}{} &  \\
    Un    & =     & Xn    &       &       &       &       & …     & +     & Xn-1  &  \\
    Sn    & =     &       &       &       &       &       &       &       &       & Xn \\
    \end{tabular}%
  \label{tab:addlabel}%
\end{table}%

\end{document}

Please watch out X1 and X2 vertical alignment. – Feb 13 '19 at 16:07 — , Feb 13 '19 at 16:07

score 2 · Accepted Answer · answered Feb 14 '19 at 01:21

You can put a bunch of [b]ottom-aligned constructions next to one another, separated by a \vrule:

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\[
  \begin{aligned}[b]
    U_1 &= X_1 \\
    U_2 &= X_2 \\
    U_3 &= X_3 \\
    \\ \\
    U_n &= X_n \\
      S &= \mathstrut
  \end{aligned}
  {\vrule\begin{aligned}[b]
    \mathstrut \\ {}+ X'_1 \\ \mathstrut \\ \mathstrut \\ \mathstrut \\ \mathstrut
  \end{aligned}}
  {\vrule\begin{aligned}[b]
    \mathstrut \\ {}+ X'_2 \\ \mathstrut \\ \mathstrut \\ \mathstrut
  \end{aligned}}
  {\vrule\begin{aligned}[b]
    \mathstrut \\ {}+ X'_3 \\ \mathstrut \\ \mathstrut
  \end{aligned}}
  {\vrule\begin{aligned}[b]
    \mathstrut \\ \quad\cdots\quad \\ \mathstrut
  \end{aligned}}
  {\vrule\begin{aligned}[b]
    \mathstrut \\ {}+ X'_{n-1}
  \end{aligned}}
\]

\end{document}

The \vrules are grouped with an aligned that has a blank top row (using \mathstrut). The \vrule will stretch the vertical length of the construction by default.

Draw vertical line down aligned equation

4 Answers4

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