# Is there a non-matrix Lie group?

I'm new to Lie Groups, but all the examples I found are matrix groups. Can someone show a non-matrix Lie group?

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Example: en.wikipedia.org/wiki/Metaplectic_group. Proof that $\mathrm{Mp}(2, \Bbb R)$ is not a matrix group: concretenonsense.wordpress.com/2009/07/10/…. –  Henry T. Horton Oct 2 '12 at 18:03
See also this related discussion on MO: mathoverflow.net/questions/64195/… –  Henry T. Horton Oct 2 '12 at 18:05
I misinterpreted the question. It certainly does. The universal cover of $\mathbf{SL}_2(\mathbf{R})$ is a good example. –  Luis Costa Oct 2 '12 at 18:18