I am trying to split an equation over multiple lines. To improve readability, I want to make the second line line up with the right side of the left brace of the first line as is almost achieved in the image below. Doing this, I stumbled upon the issue that alignment marks (&
) do not work inside \left
, \right
. This question pointed me to the \biggl
operators that circumvent this problem. I was however wondering: is there a way to make alignment marks inside \left
and \right
work as expected?
Example and code to generate it:
\documentclass[twocolumn]{article}
\usepackage{amsmath}
\begin{document}
\def\leftside{\upsilon_{N, cw}(\omega)}
\def\prefix{- \frac{1}{\Delta} \Gamma}
\def\firstline{i\omega - \xi_{cc}\bar N + \frac{\Delta\Gamma}{2}}
\def\lastline{{+}\:\left.\frac{|\kappa|^2}{2\Delta\Gamma} \exp(-i\omega\tau)}
\begin{align}
\begin{split}
\leftside =& \prefix
\begin{aligned}[t]
&\left(\firstline\right.\\
&\left.\lastline\right)
\end{aligned}
\end{split}
\end{align}
\end{document}
Best Answer
There's a solution with Sébastien Gouezel's
\MTkillspecial
command and\DeclarePairedDelimiter
command frommathtools
: I define a\brkparens
command, which adds an implicit pair of\left … \right
in its starred version. For fine tuning, the non-starred version accepts an optional argument (\big, \Big
, &c.):