# Right aligned first column in a cases environment

Is there a simple way to obtain a right aligned first column in the cases environment. As far as I can see, mathtools does not add such an option.

(This question might be read as a request for enhancement on mathtools... :) )

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The mathtools package actually provides this extension as a feature already! Cases can be created using the following syntax:

\newcases{<case name>}{<space>}{%
<left col align>}{<right col align>}{<left delim>}{<right delim>}


The regular dcases case is defined in the following way:

\newcases{dcases}{\quad}{%
$\m@th\displaystyle{##}$\hfil}{$\m@th\displaystyle{##}$\hfil}{\lbrace}{.}


Consequently, you would probably be interested in:

\makeatletter
\hfil$\m@th\displaystyle{##}$}{$\m@th\displaystyle{##}$\hfil}{\lbrace}{.}

Remember to add \makeatletter before and \makeatother after using this. I've updated my answer to include this. – Werner Sep 5 '11 at 6:23