How can I align multiple aligned environments?

Question

I have this equations:

\begin{align}
  \begin{aligned}
    x&=y & z&=w & k&=j \\
    a&=b & c&=d & e&=f \\
  \end{aligned}
  \\
\begin{aligned}
    x+a&=y+b & z+c&=w+d & z+x&=b \\
    a+q&=b+w & c+e&=d+r & e+t&=f+y \\
\end{aligned}
\end{align}

I want all columns to be aligned each others like in the following example:

I have tried to adjust spaces by hands in the following horrible way:

\begin{align}
 x&=y & z&=w & k&=j\nonumber\\[-.25\baselineskip]
 \\[-.75\baselineskip]
 a&=b & c&=d & e&=f
 \nonumber\\
 x+a&=y+b & z+c&=w+d & z+x&=b\nonumber\\[-.25\baselineskip]
 \\[-.75\baselineskip]
 a+q&=b+w & c+e&=d+r & e+t&=f+y\nonumber
\end{align}

Is there a TeXnician solution to do this?

Please clarify what you're trying to achieve. Should the first three rows of equations be given just 1 equation number, while giving another number to the final row? — Mico, Sep 11 '19 at 14:29
Is placing the (C.17) and (C.18) equation numbers slightly above rows 2 and 4 intentional? — Mico, Sep 11 '19 at 14:36
If you can put them in all in one environment, use alginat instead. Otherwise you need to determine the widest element of each and then use \makebox. — Peter Grill, Sep 11 '19 at 14:36
@Mico I have placed equation numbers by hands as try. First two equations are numbered as C.17, second two as C.18. — Onner Irotsab, Sep 11 '19 at 14:44
I'd be inclined to add a few points of extra space between the first and second aligned to make the grouping more obvious. — barbara beeton, Sep 11 '19 at 18:56

score 3 · Answer 1 · answered Sep 11 '19 at 15:21

You need to capture the widths of the widest elements in each of your equations. Then you can use those widths to impose alignment between elements that aren't as wide.

Below I use a slight modification to eqparbox via \eqmathbox[<tag>][<align>]{<math>} which stores the maximum width of each <tag>ged box with varying <math> content. Within the box you can change the <align>ment as needed (left, centre or right).

\documentclass{article}

\usepackage{eqparbox,xparse,amsmath}

% https://tex.stackexchange.com/a/34412/5764
\makeatletter
\NewDocumentCommand{\eqmathbox}{o O{c} m}{%
  \IfValueTF{#1}
    {\def\eqmathbox@##1##2{\eqmakebox[#1][#2]{$##1##2$}}}
    {\def\eqmathbox@##1##2{\eqmakebox{$##1##2$}}}
  \mathpalette\eqmathbox@{#3}
}
\makeatother

\begin{document}

\begin{gather}
  \begin{aligned}
    \eqmathbox[ll][r]{x} &= \eqmathbox[lr][l]{y} & 
      \eqmathbox[cl][r]{z} &= \eqmathbox[cr][l]{w} & 
      \eqmathbox[rl][r]{k} &= \eqmathbox[rr][l]{j} \\
    a &= b & c &= d & e &= f \\
  \end{aligned}
  \\
  \begin{aligned}
    x + a &= \eqmathbox[lr]{y + b + c} & 
      \eqmathbox[cl]{z + c + e} &= w + d & 
      z + x &= \eqmathbox[rr]{b + i + j} \\
    \eqmathbox[ll]{a + q + d} &= b + w & 
      c + e &= \eqmathbox[cr]{d + r + o} &
      \eqmathbox[rl]{p + e + t} &= f + y
  \end{aligned}
\end{gather}

\end{document}

How can I align multiple aligned environments?

1 Answers1