How to get a vectors components be a labeled equation?

Question

Basically I would like to have the following in a single line instead of the line break right before \begin{alignat}

$\begin{pmatrix}
component1 \\ component2
\end{pmatrix}=$\begin{alignat}{2}
0 \label{eq:first}\\    
0 \label{eq:second}
\end{alignat}

So, how can I use a vectors components to reference/label it like an equation?

Answer 1

I was able to adapt this answer to this context. It seems a bit hacky, but appears to do the job, and even works with hyperref.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\newsavebox{\mymatrix}
\begin{align} \sbox{\mymatrix}{$\displaystyle
    \begin{pmatrix}
    \mathit{component}_1 \\ \mathit{component}_2
    \end{pmatrix} \hspace{1ex} = \hspace{2ex}
$}\raisebox{-.5\ht\mymatrix}[0pt][0pt]{\usebox{\mymatrix}}
    0 \label{eggs} \\
    0 \label{wine}
\end{align}
Now, I refer to \eqref{eggs} and \eqref{wine}.
\end{document}

If you want to place delimiters around the second vector, you can place the entire equation into the \mymatrix box and blank space into the second part, as follows:

\newsavebox{\mymatrix}
\begin{align} \sbox{\mymatrix}{$\displaystyle
    \begin{pmatrix}
    \mathit{component}_1 \\ \mathit{component}_2
    \end{pmatrix} = \begin{pmatrix}
    0 \\
    0
    \end{pmatrix}
$}\raisebox{-.5\ht\mymatrix}[0pt][0pt]{\usebox{\mymatrix}}
 \label{eggs} \\
 \label{wine}
\end{align}

This method is a little cleaner, and might be better even if you don't want to delimit the second vector.