[Tex/LaTex] Newline in a “cases” environment

casesline-breakinglyx

I have the same issue as in this question: Split-like environment inside cases environment with one difference – I would like to get the same result with LyX, using as little LaTeX code as possible. How can I do that?

Here's my formula:

\begin{cases}
\epsilon & \exists k\left[i_{k}=0\right]\\
\mbox{LCS}\left(X_{1}\left(i_{1}-1\right),X_{2}\left(i_{2}- 1\right),\ldots,X_{n}\left(i_{n}-1\right)\right)||\sigma_{1}^{i_{1}} & \sigma_{1}^{i_{1}}=\sigma_{2}^{i_{2}}=\ldots=\sigma_{n}^{i_{n}}\\
\max\left\{ \mbox{LCS}\left(X_{1}\left(i_{1}-1\right),X_{2}\left(i_{2}\right),\ldots,X_{n}\left(i_{n}\right)\right),\mbox{LCS}\left(X_{1}\left(i_{1}\right),X_{2}\left(i_{2}-1\right),\ldots,X_{n}\left(i_{n}\right)\right),\ldots,\mbox{LCS}\left(X_{1}\left(i_{1}\right),X_{2}\left(i_{2}\right),\ldots,X_{n}\left(i_{n}-1\right)\right)\right\}  & \mbox{else}\end{cases}

Best Answer

\listfiles
\documentclass{article}
\usepackage{amsmath}

\begin{document}

\[
\begin{cases}
\epsilon & \exists k\left[i_{k}=0\right]\\
\text{LCS}\left(X_{1}\left(i_{1}-1\right),X_{2}\left(i_{2}- 1\right),\ldots,X_{n}
        \left(i_{n}-1\right)\right)||\sigma_{1}^{i_{1}} \qquad
              & \sigma_{1}^{i_{1}}=\sigma_{2}^{i_{2}}=\ldots=\sigma_{n}^{i_{n}}\\
  \begin{aligned}[t]\arraycolsep=0pt
     \max\{ &
      \text{LCS}\big(X_{1}(i_1-1),X_2(i_{2}),\ldots,X_{n}(i_n)\big),\\ &
       \text{LCS}\left(X_1(i_1),X_{2}(i_2-1),\ldots,X_n(i_n)\right),\\ &
     \ldots, \\ & 
       \text{LCS}
       \left(X_{1}\left(i_{1}\right),X_{2}\left(i_{2}\right),\ldots,X_{n}
       \left(i_{n}-1\right)\right)\}
  \end{aligned}  & \text{else}
\end{cases}
\]
\end{document}

alt text

pages 18f and 56 of the Mathmode document show you the cases environemnt with linebreaks. More informations are only possible when you give an example of what you did.

Related Solutions

[Tex/LaTex] cases environment inside an array

Here's a solution which (a) uses the align* environment instead of the array environment and (b) inverts the order of the arguments inside the cases environment (as I believe that this may be closer to general usage of this environment). It also defines a macro called \abs to simplify typesetting in the body of the example.

enter image description here

\documentclass{article}
\usepackage{amsmath}
\newcommand{\abs}[1]{\left|#1\right|}
\begin{document}
\begin{align*}
p_{Y \mid H_1}(y \mid H_1) 
&= f_X(g^{-1}(y)) \abs{ \dfrac{dg^{-1}(y)}{dy} } \\ 
&= \begin{cases}
      f_X(\ln(y)) \abs{ \dfrac{d \ln(y)}{dy} } = \dfrac{f_X(\ln(y))}{y} & \text{if $y>0$}\\
      0 & \text{otherwise}
   \end{cases}
\end{align*}
\end{document}

If you want to state the condition part before the result part in the cases environment, you could write it as:

   \begin{cases}
      \text{if $y>0$} &:\  
        f_X(\ln(y)) \abs{ \dfrac{d \ln(y)}{dy} } = \dfrac{f_X(\ln(y))}{y}\\
      \text{otherwise} &:\ 0  
   \end{cases}

leading to the following result:

enter image description here

[Tex/LaTex] Cases environment compresses fractions

The package mathtools (that also loads amsmath) provides dcases and dcases*:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{equation}
\alpha_{mn} =
\begin{dcases*}
\frac{16\mu^2}{mn\pi^2[\pi^2(m^2/a^2 + n^2/b^2) - \mu^2]} &
  for $m$ and $n$ odd;\\
0\vphantom{\frac{0}{0}} & for $m$ or $n$ even;
\end{dcases*}
\end{equation}
\end{document}

enter image description here

The difference between cases and dcases is that display style is used in the latter, but not in the former. The dcases* form sets the second part in text mode, making it more convenient to type textual conditions.

The \vphantom{\frac{0}{0}} is an adjustment to make the construction more balanced. Note that you don't need \left and \right in the denominator, which would make the brackets too big.

Best Answer

Related Solutions

[Tex/LaTex] cases environment inside an array

[Tex/LaTex] Cases environment compresses fractions

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