Libera operator
From specialfunctionswiki
The Libera operator $L$ is defined by $$L\{f\}(z) = \dfrac{2}{z} \displaystyle\int_0^z f(\tau) \mathrm{d}\tau.$$
The Libera operator $L$ is defined by $$L\{f\}(z) = \dfrac{2}{z} \displaystyle\int_0^z f(\tau) \mathrm{d}\tau.$$