How to create a loop for varying the values of A, B & C according to months?

% FOR the month of January from ASHRAE-1972 MODEL 
% A,B,C are constant and depends on month value.
A = 1164;  
B = 0.149; 
C = 0.109;
theta_z = 30;
I_bn = A*exp(-B/cosd(theta_z)); 
I_b = I_bn*cosd(theta_z);
I_d = C*I_bn;

% for Feb month the values of A, B & C are-
A = 1095;  
B = 0.135; 
C = 0.119;

% How to create a loop which can calculate I_bn, I_b & I_d as per each month? 

Answer 1

[VBBV]

A, B and C are not constants, they are actually variables.

1. Define, vectors for each of the parameters, A, B and C
2. Then use a for loop to each of the parameters, A, B and C
3. Store the values into I_bn, I_b & I_d vectors for each of the months as below

months = 1:12; % assuming 12 in year !!
A = rand(1,12)*1500; % values for each month
B = rand(1,12);
C = rand(1,12);
theta_z = 30;
for i = 1: length(months)
    I_bn(i) = A(i)*exp(-B(i)/cosd(theta_z)); 
    I_b(i) = I_bn*cosd(theta_z);
    I_d(i) = C(i)*I_bn;
end

[VBBV]

You could also actually avoid a for loop and use logical indexing to calculate I_bn, I_b & I_d vectors for each of the months

[WASIM ASHRAF]

Thanks, I understood it very nicely.