LaTeX – Break in math

December 6, 2021

I would like to be able to break lines in a math environment but in a way that keeps a symbol in front of the formula.

For example, the sum (sigma) followed by a long formula. So it goes out of the page but I would like to keep the formula next to the sigma even if there’s a line break.

Here’s a snippet so you can better reproduce it.

\documentclass{article}
\usepackage{amsmath,amsfonts,amssymb,mathtools}

% allows me to increase the font size of math blocks
\usepackage{graphicx} % \scalebox
\usepackage{environ}
\NewEnviron{mymath}{%
    \[
        \scalebox{1.3}{$\BODY$}
    \]
}

\begin{document}
    Lorem ipsum dolor sit amet
    \begin{mymath}
        \sum \limits _{\substack{
            yyyyyyy,\\
            zzzzzzzz,\\
            www
        }}
        (
            xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
        ) + (
            xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
        )
    \end{mymath}
\end{document}

And here’s a screenshot of what I’m trying to achieve.

So as you can see, I’m trying to keep the second parenthesis next to the sigma but under the first parenthesis.

>Solution :

First off: don’t scale elements that contain text! If you don’t like the size of your math block, use an appropriate font size instead.

You can use the split environment from amsmath :

\documentclass{article}
\usepackage{mathtools}

\begin{document}
    Lorem ipsum dolor sit amet
    \[
    \begin{split}
        \sum \limits_{\substack{
            yyyyyyy,\\
            zzzzzzzz,\\
            www
        }}
       & (
            xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
        ) +\\
        &(
            xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
        )
    \end{split}
    \]
\end{document}