One label only for align in empheq

Question

I am using the empheq package and use align environement insied of it. For instance,

\begin{empheq}[left=\empheqlbrace]{align}
a&=b \\
E&=mc^2 + \int_a^a x\, dx
\end{empheq}

or

\begin{empheq}[left=\empheqlbrace]{align}
 a&=b &&t\\
E&=mc^2 + \int_a^a x\, dx&&y
\end{empheq}

With this syntax I obtain one label per line:

or

Is there any possibility, to only obtain one label for the two lines (located at the middle position between labels (3) and (4) (or (1) and (2))?

Almost, but In practice I use align with many alignment conditions per line (I add a new example in my original post) — Guuk, Mar 27 '24 at 10:46
Anyway, your code is not compilable, please make a complete MWE — DG', Mar 27 '24 at 10:58

score 3 · Accepted Answer · answered Mar 27 '24 at 11:47

empheq is about numbering all lines. You don't need it for this case.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
\left{
  \begin{aligned}
  a&=b \
  E&=mc^2 + \int_a^a x, dx
  \end{aligned}
\right.
\end{equation}
followed by another one
\begin{equation}
\left{
  \begin{alignedat}{2}
  a&=b                      &\hspace{4em}& t\
  E&=mc^2 + \int_a^a x, dx && y
  \end{alignedat}
\right.
\end{equation}
\end{document}

One label only for align in empheq

1 Answers1