# braced equation with multiple lines on right side, with equation numbers

I thought I'd come across a solution for my question but surprisingly (to me) I did not. I hoped an example would have been in https://en.wikibooks.org/wiki/LaTeX/Advanced_Mathematics but maybe it needs updating...

Anyway, borrowing from Werner's solution, Sub-numbering equations within array I tried to get the very last result (which I kind of did, but the spacing is horrible).

How do I attain the last result in a way that looks good? I note that the order of loading packages was important, i.e. empheq then cases

\documentclass{article}
\usepackage{empheq}
\usepackage{cases}% http://ctan.org/pkg/cases

\begin{document}

\begin{subnumcases}{x=}
a + b \\
c + d \\
e + f
\end{subnumcases}

$$\epsilon_{(3,2)} = \left\{ \begin{array}{lcr} x(z) &=& z^2 - 2\,v \\ y(z) &=& z^3 - 3\,v\,z \\ t_1 &=& 3\,v^2 \end{array} \right.$$

\begin{subnumcases}{\epsilon_{(2,3)}=}
x(z) = z^2 - 2\,v \label{eq1asfsafs} \\
y(z) = z^3 - 3\,v\,z \label{eqjfdklsafjasfkasjf}\\
t_1 = 3\,v^2 \label{ejfklasjfkldsjafkl}
\end{subnumcases}

\begin{subequations}
\begin{empheq}[left={x=}\empheqlbrace]{align}
x(z) &=& z^2 - 2\,v \label{eq1asfsafs} \\
y(z) &=& z^3 - 3\,v\,z \label{eqjfdklsafjasfkasjf}\\
t_1 &=& 3\,v^2 \label{ejfklasjfkldsjafkl}
\end{empheq}
\end{subequations}

\end{document}


I've been using lualatex if that matters...

• In the fourth group, replace the three instances of &=& with &= -- the former is appropriate for performing alignment in array settings, whereas the latter is for align settings. A separate suggestion: get rid of all instances of \, -- they aren't needed.
– Mico
Nov 21, 2017 at 3:02
• Thanks! Minor wish - can I have something like \begin{array}{lcr} effect, easily?
– nate
Nov 21, 2017 at 3:05

You're using & incorrectly inside an align-like environment:

\documentclass{article}

\usepackage{empheq}

\begin{document}

$$\setlength{\arraycolsep}{0pt} \epsilon_{(3,2)} = \left\{ \begin{array}{ l l } x(z) &{}= z^2 - 2\,v \\ y(z) &{}= z^3 - 3\,v\,z \\ t_1 &{}= 3\,v^2 \end{array} \right.$$

\begin{subequations}
\begin{empheq}[left={x=}\empheqlbrace]{align}
x(z) &= z^2 - 2\,v \\
y(z) &= z^3 - 3\,v\,z \\
t_1 &= 3\,v^2
\end{empheq}
\end{subequations}

\end{document}


align has a right-left alignment using a single &.

• Nice to have both methods!
– nate
Nov 21, 2017 at 3:15