Align an aligned environment nested into split

Question

I want to align the lines inside an aligned that is nested inside a split with the rest of the equation.

This is an example:

\usepackage{amsmath}

\begin{equation}
  \begin{split}
    \text{max:} 
      \quad & A,\\
    \text{s.t.:} 
      \quad & B,\\
            & \left.
            \begin{aligned}
            & C,\\
            & D,\\
            \end{aligned}
            \right\} \quad(\text{stuff}),\\
            & E.
  \end{split}
\end{equation}

mwe_aligned

I would like C and D in the rendering above to be aligned with A, B, and E. I understand that \left. is what creates that space, but I don't know what to replace it with (Whatever I replace it with, I get a Missing delimiter error).

score 2 · Answer 1 · 2015-04-29T00:24:53.497

2

\left. inserts \nulldelimiterspace and you need two \!s

\documentclass[a4paper, 11pt]{book}
\usepackage{amsmath}
\begin{document}
\begin{equation}
  \begin{split}
    \text{max:}
      \quad & A,\\
    \text{s.t.:}
      \quad & B,\\
            & \left.\kern-\nulldelimiterspace
            \!\!\begin{aligned}
            & C,\\
            & D,\\
            \end{aligned}
            \right\} \quad(\text{stuff}),\\
            & E.
  \end{split}
\end{equation}
\end{document}

enter image description here

edited Apr 29 '15 at 00:24

answered Apr 28 '15 at 23:11

Can you explain the two `!'s? Does that depend on the fact I use aligned? – Alessandro Cosentino Apr 29 '15 at 15:24
@AlessandroCosentino With aligned, sometimes it becomes necessary to use \!. For details on \!, read What commands are there for horizontal spacing? – Apr 29 '15 at 15:36

score 1 · Answer 2 · answered Apr 28 '15 at 22:38

Two solutions, both using the rcases environment, from mathtools. The second solution replaces the split environment with alignedat; it allows to typeset the \quadonly once.

     \documentclass[a4paper, 11pt]{book}
    \usepackage[utf8]{inputenc}
    \usepackage{fourier, heuristica}

    \usepackage{mathtools}

    \begin{document}

\begin{equation}
  \begin{split}
    \text{max:}
      \quad & A,\\
    \text{s.t.:}
      \quad & B,\\
            & \mkern-6mu
            \begin{rcases}
            C,\\
            D,\\
            \end{rcases}
            \quad(\text{stuff}),\\
            & E.
  \end{split}
\end{equation}

\begin{equation}
  \begin{alignedat}{2}
    \text{max:}
      & \quad && A, \\
    \text{s.t.:}
       & & &B, \\
  & & &\mkern-6mu
 \begin{rcases}
 C,\\
 D,\\
 \end{rcases}
 \quad(\text{stuff}), \\
             & && E.
  \end{alignedat}
\end{equation}

    \end{document}

enter image description here

score 1 · Accepted Answer · answered Apr 29 '15 at 02:03

1

Just use a nested array, so you don't really have to fiddle with the horizontal space adjustment (except for the "null delimiter" \left.):

enter image description here

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\begin{equation}
  % http://tex.stackexchange.com/a/31704/5764
  \renewcommand{\arraystretch}{1.2}
  \begin{array}{r@{\quad}l}
    \text{max:}  & A, \\
    \text{s.t.:} & B, \\
                 & \left.\kern-\nulldelimiterspace
                 \begin{array}{@{}l}
                   C, \\
                   D,
                 \end{array}\right\} \qquad \text{(stuff),} \\
                 & E.
  \end{array}
\end{equation}
\end{document}

answered Apr 29 '15 at 02:03

Werner

603,163

I see, this avoids the need to insert the two "!"s, right? – Alessandro Cosentino Apr 29 '15 at 15:23
@AlessandroCosentino: Yes. The use of @{} removes the column spacing so things line up as expected. – Werner Apr 29 '15 at 15:28
I also like the fact that I can stretch the space between the lines with this solution – Alessandro Cosentino Apr 29 '15 at 15:28
If instead of 'A' I have some math, say a summation, this is rendered as if it was inline math (basically like if it was inside $ $, instead of $$ $$, so that we understand). Is there any way to fix this? – Alessandro Cosentino Apr 29 '15 at 15:35
1

@AlessandroCosentino: See Show inline math as if it were display math; you can use \displaystyle to correct the behaviour... – Werner Apr 29 '15 at 17:08

Align an aligned environment nested into split

3 Answers3