Auto Breaking of Long Math Equations

Question

There is the package breqn for automatically breaking long math equations. I have used it, but there is a little problem that I am facing with it. When we have two different long equations that we need to separate using \\ as we do in the align environment and have aligned them using &, an error shows up. What possibly could be done so that we can take advantage of the breqn package, similar to what is provided in the align environment.

Here is the code:

\documentclass[fleqn,preprint,10pt]{elsarticle}
\usepackage{amsmath}
\usepackage{breqn}
%\setkeys{breqn}{breakdepth={1}}
\begin{document}

\begin{dmath*}
\tilde{a}_{1}=a_{{10}}\epsilon_{{6}}\epsilon_{{8}}\epsilon_{{2}}-a_{{3}}\epsilon_{{
11}}\epsilon_{{9}}\epsilon_{{2}}-2\,a_{{3}}\epsilon_{{6}}\epsilon_{{8}
}\epsilon_{{2}}+2\,a_{{10}}\epsilon_{{6}}\epsilon_{{8}}\epsilon_{{9}}-
4\,a_{{3}}\epsilon_{{6}}\epsilon_{{8}}\epsilon_{{9}}+{{\rm e}^{
\epsilon_{{3}}}}a_{{11}}\epsilon_{{9}}\epsilon_{{2}}-{{\rm e}^{2\,
\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{8}}\epsilon_{{6}}\epsilon_{{2}}
-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{9}}\epsilon_{{11}}
\epsilon_{{2}}-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}
\epsilon_{{6}}\epsilon_{{5}}+{{\rm e}^{2\,\epsilon_{{3}}-\epsilon_{{10
}}}}a_{{6}}\epsilon_{{8}}\epsilon_{{2}}-{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}\epsilon_{{6}}{\epsilon_{{9}}}^{2}-2\,{{\rm e}^
{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{9}}\epsilon_{{7}}-{{\rm e}^{3\,
\epsilon_{{10}}-3\,\epsilon_{{3}}}}a_{{4}}\epsilon_{{6}}+{{\rm e}^{2\,
\epsilon_{{3}}-\epsilon_{{10}}}}a_{{6}}\epsilon_{{4}}-{{\rm e}^{2\,
\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{5}}\epsilon_{{11}}-{{\rm e}^{
\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}\epsilon_{{7}}-2\,{{\rm e}^{
\epsilon_{{10}}-\epsilon_{{3}}}}a_{{9}}\epsilon_{{11}}\epsilon_{{9}}-2
\,{{\rm e}^{2\,\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{8}}\epsilon_{{6}
}\epsilon_{{9}}+{{\rm e}^{2\,\epsilon_{{10}}-\epsilon_{{3}}}}a_{{1}}+2
\,{{\rm e}^{2\,\epsilon_{{3}}-\epsilon_{{10}}}}a_{{6}}\epsilon_{{8}}
\epsilon_{{9}}-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}
\epsilon_{{6}}\epsilon_{{9}}\epsilon_{{2}}-2\,a_{{10}}\epsilon_{{1}}+a
_{{3}}\epsilon_{{1}}+{{\rm e}^{\epsilon_{{3}}}}a_{{11}}\epsilon_{{5}}+
2\,{{\rm e}^{\epsilon_{{10}}}}a_{{7}}\epsilon_{{9}}+{{\rm e}^{\epsilon
_{{3}}}}a_{{11}}{\epsilon_{{9}}}^{2}+a_{{10}}\epsilon_{{6}}\epsilon_{{
4}}-2\,a_{{10}}\epsilon_{{7}}\epsilon_{{9}}-a_{{3}}\epsilon_{{11}}
\epsilon_{{5}}-a_{{3}}{\epsilon_{{9}}}^{2}\epsilon_{{11}}+{{\rm e}^{
\epsilon_{{10}}}}a_{{7}}\epsilon_{{2}}-2\,a_{{3}}\epsilon_{{6}}
\epsilon_{{4}}-a_{{10}}\epsilon_{{7}}\epsilon_{{2}},\\
\tilde{a}_{2}=\,-a_{{10}}\epsilon_{{2}}+a_{{3}}\epsilon_{{2}}+{{\rm e}^{\epsilon_{{10}
}-\epsilon_{{3}}}}a_{{2}}\\
\tilde{a_{3}}=\,-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}{\epsilon}^{2}a_{{9}}-{
{\rm e}^{2\,\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{5}}\epsilon_{{2}}+2
\,{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}\epsilon_{{9}}
\epsilon_{{2}}+2\,a_{{3}}\epsilon_{{8}}\epsilon_{{2}}-2\,a_{{10}}
\epsilon_{{8}}\epsilon_{{2}}+2\,a_{{10}}\epsilon_{{5}}\epsilon_{{2}}-2
\,a_{{3}}\epsilon_{{5}}\epsilon_{{2}}+{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}{\epsilon_{{9}}}^{2}+{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}\epsilon_{{5}}+{{\rm e}^{2\,\epsilon_{{10}}-2\,
\epsilon_{{3}}}}a_{{8}}\epsilon_{{2}}+2\,{{\rm e}^{2\,\epsilon_{{10}}-
2\,\epsilon_{{3}}}}a_{{8}}\epsilon_{{9}}-2\,{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{9}}\epsilon_{{8}}-{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}\epsilon_{{8}}+4\,a_{{3}}\epsilon_{{8}}\epsilon
_{{9}}-4\,a_{{10}}\epsilon_{{8}}\epsilon_{{9}}-{\epsilon}^{2}a_{{3}}
\epsilon_{{9}}+{\epsilon}^{2}a_{{10}}\epsilon_{{9}}+{{\rm e}^{3\,
\epsilon_{{10}}-3\,\epsilon_{{3}}}}a_{{4}}+3\,a_{{3}}\epsilon_{{4}}-3
\,a_{{10}}\epsilon_{{4}}
\end{dmath*}
Now see following using environment using align
\begin{align*}
\tilde{a}_{1}=&\,a_{{10}}\epsilon_{{6}}\epsilon_{{8}}\epsilon_{{2}}-a_{{3}}\epsilon_{{
11}}\epsilon_{{9}}\epsilon_{{2}}-2\,a_{{3}}\epsilon_{{6}}\epsilon_{{8}
}\epsilon_{{2}}+2\,a_{{10}}\epsilon_{{6}}\epsilon_{{8}}\epsilon_{{9}}-
4\,a_{{3}}\epsilon_{{6}}\epsilon_{{8}}\epsilon_{{9}}+{{\rm e}^{
\epsilon_{{3}}}}a_{{11}}\epsilon_{{9}}\epsilon_{{2}}\\
&-{{\rm e}^{2\,
\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{8}}\epsilon_{{6}}\epsilon_{{2}}
-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{9}}\epsilon_{{11}}
\epsilon_{{2}}-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}
\epsilon_{{6}}\epsilon_{{5}}+{{\rm e}^{2\,\epsilon_{{3}}-\epsilon_{{10
}}}}a_{{6}}\epsilon_{{8}}\epsilon_{{2}}\\
&-{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}\epsilon_{{6}}{\epsilon_{{9}}}^{2}-2\,{{\rm e}^
{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{9}}\epsilon_{{7}}-{{\rm e}^{3\,
\epsilon_{{10}}-3\,\epsilon_{{3}}}}a_{{4}}\epsilon_{{6}}+{{\rm e}^{2\,
\epsilon_{{3}}-\epsilon_{{10}}}}a_{{6}}\epsilon_{{4}}-{{\rm e}^{2\,
\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{5}}\epsilon_{{11}}\\
&-{{\rm e}^{
\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}\epsilon_{{7}}-2\,{{\rm e}^{
\epsilon_{{10}}-\epsilon_{{3}}}}a_{{9}}\epsilon_{{11}}\epsilon_{{9}}-2
\,{{\rm e}^{2\,\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{8}}\epsilon_{{6}
}\epsilon_{{9}}+{{\rm e}^{2\,\epsilon_{{10}}-\epsilon_{{3}}}}a_{{1}}\\&+2
\,{{\rm e}^{2\,\epsilon_{{3}}-\epsilon_{{10}}}}a_{{6}}\epsilon_{{8}}
\epsilon_{{9}}-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}
\epsilon_{{6}}\epsilon_{{9}}\epsilon_{{2}}-2\,a_{{10}}\epsilon_{{1}}+a
_{{3}}\epsilon_{{1}}+{{\rm e}^{\epsilon_{{3}}}}a_{{11}}\epsilon_{{5}}\\&+
2\,{{\rm e}^{\epsilon_{{10}}}}a_{{7}}\epsilon_{{9}}+{{\rm e}^{\epsilon
_{{3}}}}a_{{11}}{\epsilon_{{9}}}^{2}+a_{{10}}\epsilon_{{6}}\epsilon_{{
4}}-2\,a_{{10}}\epsilon_{{7}}\epsilon_{{9}}\\&-a_{{3}}\epsilon_{{11}}
\epsilon_{{5}}-a_{{3}}{\epsilon_{{9}}}^{2}\epsilon_{{11}}+{{\rm e}^{
\epsilon_{{10}}}}a_{{7}}\epsilon_{{2}}-2\,a_{{3}}\epsilon_{{6}}
\epsilon_{{4}}-a_{{10}}\epsilon_{{7}}\epsilon_{{2}},\\
\tilde{a}_{2}=&\,-a_{{10}}\epsilon_{{2}}+a_{{3}}\epsilon_{{2}}+{{\rm e}^{\epsilon_{{10}
}-\epsilon_{{3}}}}a_{{2}}\\
\tilde{a_{3}}=&\,-{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}{\epsilon}^{2}a_{{9}}-{
{\rm e}^{2\,\epsilon_{{10}}-2\,\epsilon_{{3}}}}a_{{5}}\epsilon_{{2}}+2
\,{{\rm e}^{\epsilon_{{10}}-\epsilon_{{3}}}}a_{{2}}\epsilon_{{9}}
\epsilon_{{2}}+2\,a_{{3}}\epsilon_{{8}}\epsilon_{{2}}-2\,a_{{10}}
\epsilon_{{8}}\epsilon_{{2}}\\
&+2\,a_{{10}}\epsilon_{{5}}\epsilon_{{2}}-2
\,a_{{3}}\epsilon_{{5}}\epsilon_{{2}}+{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}{\epsilon_{{9}}}^{2}+{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}\epsilon_{{5}}+{{\rm e}^{2\,\epsilon_{{10}}-2\,
\epsilon_{{3}}}}a_{{8}}\epsilon_{{2}}+2\,{{\rm e}^{2\,\epsilon_{{10}}-
2\,\epsilon_{{3}}}}a_{{8}}\epsilon_{{9}}\\
&-2\,{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{9}}\epsilon_{{8}}-{{\rm e}^{\epsilon_{{10}}-
\epsilon_{{3}}}}a_{{2}}\epsilon_{{8}}+4\,a_{{3}}\epsilon_{{8}}\epsilon
_{{9}}-4\,a_{{10}}\epsilon_{{8}}\epsilon_{{9}}-{\epsilon}^{2}a_{{3}}
\epsilon_{{9}}+{\epsilon}^{2}a_{{10}}\epsilon_{{9}}\\
&+{{\rm e}^{3\,
\epsilon_{{10}}-3\,\epsilon_{{3}}}}a_{{4}}+3\,a_{{3}}\epsilon_{{4}}-3
\,a_{{10}}\epsilon_{{4}}
\end{align*}
Basically what I want to do is to use dmath environment just like above.
\end{document}

Answer 1

You could insert \nobreak instructions after \tilde{a}_{2} and \tilde{a_{3}}, respectively. (The latter expression should probably be \tilde{a}_{3}, right?)

Answer 2

What you are looking for is dgroup. If you want to align several equations, you put each of them in a dmath environment and all the dmath environments are put inside a dgroup environment. Nobody will have understood this last sentence, but the following example will make it clear.

\documentclass{article}
\usepackage{breqn}
% Macro for Euler's number
\newcommand*\ee{\mathrm{e}}
\begin{document}

\begin{dgroup*}
  \begin{dmath*}
    \tilde{a}_{1}
    = a_{10} \epsilon_6 \epsilon_8 \epsilon_2
    - a_3 \epsilon_{11} \epsilon_9 \epsilon_2
    - 2 a_3 \epsilon_6 \epsilon_8 \epsilon_2
    + 2 a_{10} \epsilon_6 \epsilon_8 \epsilon_9
    - 4 a_3 \epsilon_6 \epsilon_8 \epsilon_9
    + \ee^{\epsilon_3} a_{11} \epsilon_9 \epsilon_2
    - \ee^{2 \epsilon_{10} - 2 \epsilon_3} a_8 \epsilon_6 \epsilon_2
    - \ee^{\epsilon_{10}-\epsilon_3} a_9\epsilon_{11} \epsilon_2
    - \ee^{\epsilon_{10}-\epsilon_3} a_2 \epsilon_6 \epsilon_5
    + \ee^{2 \epsilon_3 - \epsilon_{10}} a_6 \epsilon_8 \epsilon_2
    - \ee^{\epsilon_{10} - \epsilon_3} a_2 \epsilon_6 \epsilon_9^2
    - 2 \ee^{\epsilon_{10}-\epsilon_3} a_9 \epsilon_7
    - \ee^{3 \epsilon_{10} - 3 \epsilon_3} a_4 \epsilon_6
    + \ee^{2 \epsilon_3 - \epsilon_{10}} a_6 \epsilon_4
    - \ee^{2 \epsilon_{10} - 2 \epsilon_3} a_5 \epsilon_{11}
    - \ee^{\epsilon_{10} - \epsilon_3} a_2 \epsilon_7
    - 2 \ee^{\epsilon_{10} - \epsilon_3} a_9 \epsilon_{11} \epsilon_9
    - 2 \ee^{2 \epsilon_{10} - 2 \epsilon_3} a_8 \epsilon_6 \epsilon_9
    + \ee^{2 \epsilon_{10} - \epsilon_3} a_1
    + 2 \ee^{2 \epsilon_3 - \epsilon_{10}} a_6 \epsilon_8 \epsilon_9
    - \ee^{\epsilon_{10} - \epsilon_3} a_2 \epsilon_6 \epsilon_9 \epsilon_2
    - 2 a_{10} \epsilon_1
    + a_3 \epsilon_1
    + \ee^{\epsilon_3} a_{11} \epsilon_5
    + 2 \ee^{\epsilon_{10}} a_7 \epsilon_9
    + \ee^{\epsilon_3} a_{11} \epsilon_9^2
    + a_{10} \epsilon_6 \epsilon_4
    - 2 a_{10} \epsilon_7 \epsilon_9
    - a_3 \epsilon_{11} \epsilon_5
    - a_3 \epsilon_9^2 \epsilon_{11}
    + \ee^{\epsilon_{10}} a_7 \epsilon_2
    - 2 a_3 \epsilon_6 \epsilon_4
    - a_{10} \epsilon_7 \epsilon_2 ,
  \end{dmath*}
  \begin{dmath*}
    \tilde{a}_2
    = - a_{10} \epsilon_2
    + a_3 \epsilon_2
    + \ee^{\epsilon_{10} - \epsilon_3} a_2
  \end{dmath*}
  \begin{dmath*}
    \tilde{a}_3
    = - \ee^{\epsilon_{10} - \epsilon_3} \epsilon^2 a_9
    - \ee^{2 \epsilon_{10} - 2 \epsilon_3} a_5 \epsilon_2
    + 2 \ee^{\epsilon_{10} - \epsilon_3} a_2 \epsilon_9 \epsilon_2
    + 2 a_3 \epsilon_8 \epsilon_2
    - 2 a_{10} \epsilon_8 \epsilon_2
    + 2 a_{10} \epsilon_5 \epsilon_2
    - 2 a_3 \epsilon_5 \epsilon_2
    + \ee^{\epsilon_{10} - \epsilon_3} a_2 \epsilon_9^2
    + \ee^{\epsilon_{10} - \epsilon_3} a_2 \epsilon_5
    + \ee^{2 \epsilon_{10} - 2 \epsilon_3} a_8 \epsilon_2
    + 2 \ee^{2 \epsilon_{10} - 2 \epsilon_3} a_8 \epsilon_9
    - 2 \ee^{\epsilon_{10} - \epsilon_3} a_9 \epsilon_8
    - \ee^{\epsilon_{10} - \epsilon_3} a_2 \epsilon_8
    + 4 a_3 \epsilon_8 \epsilon_9
    - 4 a_{10} \epsilon_8 \epsilon_9
    - \epsilon^2 a_3 \epsilon_9
    + \epsilon^2 a_{10} \epsilon_9
    + \ee^{3 \epsilon_{10} - 3 \epsilon_3} a_4
    + 3 a_3 \epsilon_4
    - 3 a_{10} \epsilon_4
  \end{dmath*}
\end{dgroup*}

\end{document}