How to make \left, \right pairs of delimiter work over multiple lines?

Question

I have a very long equation that must be separated into two lines, and it has several pairs of nesting \left \right delimiters. Unfortunately, it seems that they need to be on the same line in order for them to work.

Also I'm using the align environment because I need the aligning functionality. Is there a way to have the size of delimiters automatically adjusted over multiple lines?

Answer 1

You can't.

You can use some thing like \biggl, \biggr, or \left.\vphantom{...}\right). For example:

\[
\begin{split}
a &= \left( \frac12 + \frac13 + \frac14 \right. \\
  &\quad \left. {}+ a + b + c \vphantom{\frac12}\right)
\end{split}
\]

Answer 2

The solution for me was to use virtual dot delimiters

\frac{\partial F}{\partial x} &= \left[ \frac{\partial y}{\partial z} \right. \\
                              &* \left. \frac{\partial z}{\partial x} \right]

which was the comment posted by percusse in this question which was marked as a duplicate.

The virtual dot delimiters are in Leo Liu's answer above, but a TeX n00b like me wouldn't have seen it.

FYI Sphinx-1.1.3 already supports multi-line math with the math directive using the AmSMath LaTeX package, i.e. breqn is not necessary.

Answer 3

The breqn package is a package that defines a set of new math environments, with the purpose of enabling automatic line breaking of displayed math. These new environments also let you have \left and \right on different lines, though it is not the main goal of the package.

Note that the package has several known problems and incompatibilities, so depending on your use case it might not be for you. I recommend a look at the manual.

---

The example below is one where you definitely shouldn't use \left and \right in the first place, but it serves to illustrate that it works. The dmath environment is similar to equation.

\documentclass{article}
\usepackage{geometry}
\geometry{a5paper, margin=5cm}
\usepackage{breqn}
\begin{document}
Automatic breaking:
\begin{dmath}
55 - \left(1+2+3+4+5+6+7+8+9+10\right) = 0
\end{dmath}
Manually breaking a line seems to work as well:
\begin{dmath}
55 - \left(1+2+3+4+\5+6+7+8+9+10\right) = 0
\end{dmath}
\end{document}

Answer 4

Have a look at the nath package.

Answer 5

I had the same problem. I wanted to show this equation

\begin{equation*}
    V_{sal} = -\left(1.V_8 + \frac{1}{2}.V_7 + \frac{1}{8}.V_6 +\frac{1}{8}.V_5  + \frac{1}{16}.V_4 \right.\\
     \left. + \frac{1}{32}.V_3 + \frac{1}{64}.V_2 + \frac{1}{128}.V_1\right) 
\end{equation*}

but since it is too long (in a two column document), I used multline enviroment but it gives an error (something like Missing \right. inserted. \end{multline*} or Extra \right. \end{multline*}). I solved it with this new code

\begin{multline*}
V_{sal} = -\left(1.V_8 + \frac{1}{2}.V_7 + \frac{1}{8}.V_6 +\frac{1}{8}.V_5  + \frac{1}{16}.V_4 \right.\\
 \left. + \frac{1}{32}.V_3 + \frac{1}{64}.V_2 + \frac{1}{128}.V_1\right) 
\end{multline*}

Note that I added a \right. at the end of the first row and \left. at the beginning of the second row.

Answer 6

The previous "automated" solutions all use certain packages that have compatibility issues with amsmath. Here is a sort-of-automated solution that does not require additional packages.

This solution uses \vphantom and is in essence the same as the previous answers using this command.

% split \left and \right across two lines
% use only between \[ and \] (modify as needed for \begin{equation}\end{equation}, etc.)
\newcommand\MatchBrackets[2]{\left[#1\vphantom{#2}\right.\]\[\left.\vphantom{#1}#2\right]}
\newcommand\MatchParentheses[2]{\left(#1\vphantom{#2}\right.\]\[\left.\vphantom{#1}#2\right)}

Usage:

\[\nabla h=\MatchParentheses{\int_0^{e^5}e^{-z^2}dz+\frac12\cdot\cos\left(\frac12\cdot x\right)\cdot\cos(y),}{-\frac12\cdot\cos\left(\cos\left(\frac12\cdot y\right)\right)\cdot\sin\left(\frac12\cdot y\right)-\sin(x)\cdot\sin(y)}\]

(Idea taken from Wintz's comment here. Example modified from zdim's answer here.)