Hi Nataly,
Follow the steps below :
x = [ 1 : 1:100];%creating a array from 1 to 100 with step of 1
Cps = 1.2;%defining constants
Cdc = 1.5;
Vout = Cps*log(x) + Cdc;%by default log in matlab calculate w.r.t to base e and when function is
%applied to array it get applied to each element.
plot(x,Vout); %plotting the distance on X axis and VOut on Y axis