How to write a simple program ??

kokey

Hi ~~~my dear friend I have a problem how to write a simple program inside a UDF . In my program , two equations be existed in a same model simultaneously . equation 1 :

eta=R*T/0.5/F*log(i*P/Io/Po2) equation 2 :

i=k/Tm*(Voc-Vcell-eta)

R ,T ,F ,P,Io,Po2,Voc,Vcell,Tm,k are constants I can't direct to calculate equation 1 and equation 2 .because , in equation 1 and equation 2 only have two unknown variables , eta and i . i wish i could get a accuracy value ( i ) from a simple program .Could you help me how to write it ??

kokey