# How can I label for a collection of equations? [duplicate]

Possible Duplicate:
Separate labels in cases

I want to label each equation in a collection of equations as in the example below. How can I do this?

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The question as you asked it is a bit difficult to understand, more so because I don't have the courage to download the PDF from the link you inserted. And probably no one sane would... Try to insert the content as a picture. –  Count Zero Oct 22 '12 at 14:53
I was crazy enough to do so. It is a cases environment, with each line numbered. I'm still not sure what the question is asking, though. –  Andrew Uzzell Oct 22 '12 at 14:55
Dear Andrew Uzzell, you understand me. –  minthao_2011 Oct 22 '12 at 15:00
I guess that subnumcases would be the answer. On the other hand, if you need to refer to all the lines, it's probably better to use only one number for the whole equation. After all, it's the definition of one function; what does (1) refer to? To "0", to "if x>0" or to both? –  egreg Oct 22 '12 at 15:27
Does this question help? –  Andrew Uzzell Oct 22 '12 at 15:28
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## marked as duplicate by Peter Grill, Thorsten, Marco Daniel, lockstep, Stefan Kottwitz♦Oct 25 '12 at 6:18

Just use \eqref{eq:first}-\eqref{eq:last} if you are using the amsmath package and (\ref{eq:first})-(\ref{eq:last}) if you do not use it.