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How I can typeset this equation with LaTeX?
This'll probably be a too specific question, but I do think this forum has the most knowledge to help me with it.
I would like to write this equation in latex

I tried it with
\begin{pmatrix}
\end{pmatrix}
Though this also gives a bracket at the end.
Would anyone be able to help me ?

casesenvironment from the amsmath package. – Ian Thompson Dec 6 '12 at 21:31cases*, since it has text on the right and I find more intuitive that way. – Manuel Dec 6 '12 at 21:34