  This is basically a summary of [Mu]. The focus of the paper is the explicit
computation of Hecke operators for period functions. In particular we compute
the matrix representations of the 2nd Hecke operator on period functions for
the full modular group $SL(2,Z)$ and the congruence subgroup $\Gamma_0(2)$.
  [Mu] Tobias M\"uhlenbruch. Hecke operators on period functions for
$\Gamma_0(N)$. Journal of Number Theory.
http://dx.doi.org/10.1016/j.jnt.2005.09.003
