Equation number in an array

Question

I want to put the equation number at the right for the following code:

\[
 \log{y_{i}} = 
\left\{
  \begin{array}{l l}
    y_{2i}^{*} & \quad \textrm{if $y_{2i}^{*}\succ0$}\\
    0 & \quad \textrm{otherwise}
  \end{array} 
    \right.
    \]

Any idea?

Do you want the individual elements in the array numbered, or the equation as a whole? — Werner, Oct 25 '13 at 18:43

score 16 · Accepted Answer · edited Jun 10 '17 at 12:55

16

Do wisely use {} to maintain readability.

\documentclass[preview,border=12pt]{standalone}
\usepackage{amsmath}
\begin{document}
\abovedisplayskip=0pt\relax% don't use this line in your production
\begin{equation}
\log y_i= 
\begin{cases}
    y_{2i}^* & \quad \text{if $y_{2i}^*\succ0$}\\
    0 & \quad \text{otherwise} 
\end{cases}
\end{equation}
\end{document}

enter image description here

edited Jun 10 '17 at 12:55

Moriambar

11,466

answered Oct 25 '13 at 18:51

kiss my armpit

36,086

4

@Metrics: It is not the alternative solution but the correct one. align is used when you have more than one equation to be aligned. – kiss my armpit Oct 25 '13 at 18:58
@Metrics: Please read align versus equation. – kiss my armpit Oct 25 '13 at 19:06
1

flalign should not be used in this case. – kiss my armpit Oct 25 '13 at 20:35

score 3 · Answer 2 · 2013-10-25T20:25:47.713

3

load package amsmath and then replace \[ ... \] by

\begin{flalign}
...
\end{flalign}

edited Oct 25 '13 at 20:25

answered Oct 25 '13 at 18:44

Equation number in an array

2 Answers2