Math & Science ⇒ How to stretch cases array?

[bkarpuz]

Dear friends,

I use the following code

Code: Select all

\begin{equation}
p(m,n):=
\begin{cases}
\displaystyle\frac{2}{9},&\mathrm{mod}(m,3)=0 \\
\displaystyle\frac{1}{9},&\text{otherwise}
\end{cases}\quad\text{for}\ (m,n)\in\mathbb{Z}_{0}^{2}.\notag
\end{equation}

But in this case, the rows of the cases array appear very closer to each other as in the following graphic.

cases-env.jpg (6.15 KiB) Viewed 7702 times

I used to the following code in preambles to stretch the rows but it did not work.

Code: Select all

\renewcommand{\arraystretch}{1.5}

If possible can you please let me know the right code for stretch the rows of the cases?

Thanks.

[localghost]

At first, please upload attachments to the forum server next time (reasons can be found in Section 2.5 of the Board Rules).

You can add some additional vertical space between the lines of the cases environment.

Code: Select all

\begin{equation*}
  p(m,n):=
  \begin{cases}
    \dfrac{2}{9},&\text{mod}(m,3)=0 \\[2\jot]
    \dfrac{1}{9},&\text{otherwise}
  \end{cases}\quad\text{for}\ (m,n)\in\mathbb{Z}_{0}^{2}.
\end{equation*}

As an alternative you could typeset the fractions with nicefrac.


Best regards
Thorsten

[bkarpuz]

Thanks localghost, it works good.
And I will use the forum's server for images next time.

[Stefan Kottwitz]

Hi,

If possible can you please let me know the right code for stretch the rows of the cases?

here's another solution for the general problem: amsmath: cases and \arraystretch.

Stefan

[phi]

The mathtools package provides an easy solution:

Code: Select all

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{mathtools}
\begin{document}
\begin{equation*}
  p(m,n) \coloneqq
  \begin{dcases}
    \frac{2}{9},&\bmod(m,3)=0 \\
    \frac{1}{9},&\text{otherwise}
  \end{dcases}
  \quad\text{for } (m,n)\in\mathbb{Z}_{0}^{2}.
\end{equation*}
\end{document}

Also note the use of the commands \coloneqq and \bmod.