# How to write multiple conditions in separate lines in braced equations?

How do I typeset something like, X = 0 if a=1 & b=1 & c= 5 & d=9 ; 0 otherwise, using those huge left braces and specifying each condition in a line (4 conditions in 4 separate lines)?

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Can you show an approximate picture of the output you wish? – egreg Oct 21 '13 at 7:37
– cmhughes Oct 21 '13 at 16:55

It's not clear to me if the conditions for X=1 are separate (logical "or") or cumulative (logical "and"). Assuming it's the former, the following two expressions may meet your needs.

\documentclass{article}
\usepackage{amsmath} % for cases environment and \text command
\begin{document}
$X = \begin{cases} 1 & \text{if a=0 or b=1 or c=5 or d=9} \\ 0 & \text{otherwise} \end{cases}$

$X = \begin{cases} 1 & \text{if a=0} \\ 1 & \text{if b=1} \\ 1 & \text{if c=5} \\ 1 & \text{if d=9} \\ 0 & \text{otherwise} \end{cases}$
\end{document}


Personally, I strongly prefer the first of these two forms -- at least for the setup you've provided. Should the conditions be more elaborate, the second form may well be the better option.

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As far as I understand, your want the following construction:

\documentclass{article}
\begin{document}

$\left\{ \begin{array}{rl} X=1 & \mbox{if a=1},\\ X=10 & \mbox{if a=2},\\ X=100 & \mbox{if a=3},\\ X=1000 &\mbox{otherwise} \end{array} \right.$

or

$\left\{ \begin{array}{ll} X=1 & \mbox{if a=1},\\ X=10 & \mbox{if a=2},\\ X=100 & \mbox{if a=3},\\ X=1000 &\mbox{otherwise} \end{array} \right.$

\end{document}


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I think OP is looking for a cases solution – percusse Oct 21 '13 at 0:01