The group $\SL(2,\R)$ acts on the upper half-plane via
**linear fractional transformation**, given by
$$
\begin{pmatrix}a&b\\c&d \end{pmatrix}(z)
=
\frac{a z + b}{c z + d} .
$$

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**Knowl status:**

- Review status: reviewed
- Last edited by Alex J. Best on 2019-05-25 09:07:50

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