math-mode
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?
You have known Morten Høgholm's mathtools, then you can try his breqn package:
\documentclass{article}
\usepackage{breqn}
\begin{document}
\hsize=12cm
\begin{dmath}
f(x) = x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x = x*c
\end{dmath}
\hsize=6cm
\begin{dmath}
f(x) = x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x = x*c
\end{dmath}
\hsize=3cm
\begin{dmath}
f(x) = x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x = x*c
\end{dmath}
\end{document}
The following example uses package zref to remember the size of the math formula in labels. Package mleftright is used to reduce the additional horizontal spacing by \left and \right.
Inside a complex math block, the following macros can be used:
\mzleft{<label>}{<left delimiter>}{<math formula>}
\mzright{<label>}{<math formula>}{<right delimiter>}
The macros can be nested, The <label> is needed to identify the pairs of delimiters. Inside the math block (math environment, ...) the <label> names for the pairs must be unique. After the math block \mzreset can be called. It frees the <label> names and they can be reused.
Example file:
\documentclass{article}
\usepackage{amsmath}
\usepackage{mleftright}
\usepackage{zref-base}
\makeatletter
\zref@newprop{mzheight}[0pt]{\the\ht\z@}
\zref@newprop{mzdepth}[0pt]{\the\dp\z@}
\newcount\c@@mz
\newcommand*{\the@mz}{mz\the\c@@mz}
\newcommand*{\@mz@list}{}
\let\@mz@do\relax
\newcommand*{\mzreset}{%
\begingroup
\def\@mz@do##1{%
\global\expandafter\let\csname mz@##1\endcsname\relax
}%
\@mz@list
\global\let\@mz@list\@empty
\endgroup
}
\newcommand*{\mzleft}[3]{%
\@ifundefined{mz@#1}{%
\global\advance\c@@mz\@ne
\expandafter\xdef\csname mz@#1\endcsname{\the@mz}%
\xdef\@mz@list{\@mz@list\@mz@do{#1}}%
}{}%
\expandafter\let\expandafter\@mz\csname mz@#1\endcsname
\mleft#2%
\expandafter\mathpalette\expandafter{%
\expandafter\@mzleft\expandafter{\@mz}%
}{#3}%
\mright.\kern-\nulldelimiterspace
}
\newcommand*{\mzright}[3]{%
\kern-\nulldelimiterspace
\@ifundefined{mz@#1}{%
\@latex@warning{Missing \string\mzleft{#1}}%
\mleft.#2\mright#3%
}{%
\expandafter\let\expandafter\@mz\csname mz@#1\endcsname
\mleft.%
\expandafter\mathpalette\expandafter{%
\expandafter\@mzright\expandafter{\@mz}%
}{#2}%
\mright#3%
}%
}
\newcommand*{\@mzleft}{%
\@mzleftright lr%
}
\newcommand*{\@mzright}{%
\@mzleftright rl%
}
\newcommand*{\@mzleftright}[5]{%
\sbox0{$\m@th#4{}#5{}$}%
\ifmeasuring@
\else
\begingroup
\let\@auxout\@mainaux
\zref@labelbyprops{#3#1}{mzheight,mzdepth}%
\endgroup
\fi
\zifrefundefined{\@mz #2}{%
}{%
\dimen@=\zref@extract{#3#2}{mzheight}\relax
\ifdim\dimen@>\ht0 %
\ht0=\dimen@
\fi
\dimen@=\zref@extract{#3#2}{mzdepth}\relax
\ifdim\dimen@>\dp0 %
\dp0=\dimen@
\fi
}%
\copy0\relax
}
\makeatother
\begin{document}
\begin{align*}
\begin{split}
z = \mzleft{a}({ a + b + c +} \\
\mzright{a}{{}+ \frac{d}{e}})
\end{split}
\end{align*}
\mzreset
\begin{align*}
\begin{split}
z = \mzleft{a}{[}{%
a + b + \frac{c}{d} +
\mzleft{b}{(}{
\int_0^\infty \mathrm{d}x
}
} \\
\mzright{b}{
+ y}{)
}
\mzright{a}{
+ \frac{\displaystyle\sum_{i=0}^{100}i}{e}
}{]}
\end{split}
\end{align*}
\end{document}
Best Answer
The
breqnpackage 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\leftand\righton 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
\leftand\rightin the first place, but it serves to illustrate that it works. Thedmathenvironment is similar toequation.