# Which one is recommended to split, continue and align a long equation?

In my investigation, the outputs are identical as follows.

## Version 1:

Using aligned.

\begin{align*}
\framebox[6cm]{Top LHS}\\
\framebox[5cm]{Middle LHS}\\
\framebox[4cm]{Bottom LHS}
&= \!
\begin{aligned}[t]
&\framebox[6cm]{Top RHS 1}\\
&\framebox[5cm]{Middle RHS 1}\\
&\framebox[7cm]{Bottom RHS 1}
\end{aligned}\\
&= \!
\begin{aligned}[t]
&\framebox[6cm]{Top RHS 2}\\
&\framebox[5cm]{Middle RHS 2}\\
&\framebox[7cm]{Bottom RHS 2}
\end{aligned}
\end{align*}


## Version 2:

Using \hphantom.

\begin{align*}
\framebox[6cm]{Top LHS}\\
\framebox[5cm]{Middle LHS}\\
\framebox[4cm]{Bottom LHS}
&=\framebox[6cm]{Top RHS 1}\\
&\hphantom{{}={}}\framebox[5cm]{Middle RHS 1}\\
&\hphantom{{}={}}\framebox[7cm]{Bottom RHS 1}\\
&=\framebox[6cm]{Top RHS 2}\\
&\hphantom{{}={}}\framebox[5cm]{Middle RHS 2}\\
&\hphantom{{}={}}\framebox[7cm]{Bottom RHS 2}
\end{align*}


## Complete Code:

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

\begin{align*}
\framebox[6cm]{Top LHS}\\
\framebox[5cm]{Middle LHS}\\
\framebox[4cm]{Bottom LHS}
&= \!
\begin{aligned}[t]
&\framebox[6cm]{Top RHS 1}\\
&\framebox[5cm]{Middle RHS 1}\\
&\framebox[7cm]{Bottom RHS 1}
\end{aligned}\\
&= \!
\begin{aligned}[t]
&\framebox[6cm]{Top RHS 2}\\
&\framebox[5cm]{Middle RHS 2}\\
&\framebox[7cm]{Bottom RHS 2}
\end{aligned}
\end{align*}

\newpage

\begin{align*}
\framebox[6cm]{Top LHS}\\
\framebox[5cm]{Middle LHS}\\
\framebox[4cm]{Bottom LHS}
&=\framebox[6cm]{Top RHS 1}\\
&\hphantom{{}={}}\framebox[5cm]{Middle RHS 1}\\
&\hphantom{{}={}}\framebox[7cm]{Bottom RHS 1}\\
&=\framebox[6cm]{Top RHS 2}\\
&\hphantom{{}={}}\framebox[5cm]{Middle RHS 2}\\
&\hphantom{{}={}}\framebox[7cm]{Bottom RHS 2}
\end{align*}

\end{document}


Any positive suggestions are welcome.

-

1. It achieves the desired alignment with the semantics made for alignments (align and aligned). Using hand made white space (the \hphantoms) is only a last resort for me: what purpose do these alignment constructs have when I have to manually adjust stuff with white space?!
2. It is more robust. Suppose you find out, after typing the second version, that = is the wrong relation, and needs to be replaced with a wider relation like \Coloneqq. Then you have to change all the \hphantoms in the second solution, while the first solution still works.