%%
%% The LaTeX Companion, 3ed
%%
%% Example 11-2-13 on page II-138 in "Multiple alignments: \protect \nxLenv {align} and \protect \nxLenv {flalign}".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See
https://www.latex-project.org/lppl.txt for details.
%%
\documentclass{tlc3examargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{231.0pt}
%StartShownPreambleCommands
\usepackage{amsmath}
%StopShownPreambleCommands
\begin{document}
This example has two column-pairs.
\begin{align} \text{Compare }
x^2 + y^2 &= 1 &
x^3 + y^3 &= 1 \\
x &= \sqrt {1-y^2} &
x &= \sqrt[3]{1-y^3}
\end{align}
This example has three column-pairs.
\begin{align}
x &= y & X &= Y &
a &= b+c \\
x' &= y' & X' &= Y' &
a' &= b \\
x + x' &= y + y' &
X + X' &= Y + Y' & a'b &= c'b
\end{align}
\end{document}
