## Tee attenuator
__Zin__ desired input impedance in Ω
__Zout__ desired output impedance
__Zin = Zout__
* __a__ attenuation in dB
* __L = 10a/20__ (the loss)
* ___A = (L + 1)/(L - 1)___
* ___R2 = 2√(L \* Zin \* Zout )/(L - 1)___
* ___R1 = Zin \* A - R2___
* ___R3 = Zout \* A - R2___