MATLAB: How can this probability function be entered

Question

I'm very new to matlab. I want to take this equation and use matlab to graph it:

I used this code

The variable P is created but it has a value for the first element, then all zeros.

Answer 1

You have to vectorise your assignment for ‘P’:

k = 1.3806488E-23;
e = 6.0217657E-19;
z = 2;
Vh = 1E-3;
T1 = 25+273.15;
T2 = 37+273.15;
V = linspace(-0.1, 0.09);
VV = V-Vh;
P = 1./(1+exp(-z*e*(VV/(k*T1))));
figure(1)
plot(V, P)
grid

See Matrix vs Array Operations for details.