clc;
I1=0.5*10**-3;
V1=340*10**-3;
I2=15*10**-3;
V2=440*10**-3;
kTbyq=25*10**-3;
a=V1/kTbyq;
b=V2/kTbyq;
//log(I1/I2)==log(exp((b-a)/n));
n=(a-b)/(log(I1/I2));
disp(n);