Nested loop for matrix

Below is my code. I want to calculate the value of g where my for loop iterates for i and K. It means I hould have 6 combinations of output.However, I am only getting 3 combinations of output saved in g. Could you please provid the hint or feeback on it? Thanks!

clc
clear all;
ED = readmatrix("Data filteration1.xlsx");
ki = 0.0042;    %%current temp coeff
Ns=72;          %%72cells in series and 1 in parellel
Np=1;
Ego=1.1;
K= 1.380*10^-23;
q= 1.602*10^-19;
Voc=48.37;
Isc=10.27;
G=[1000 800];
Tck = [25+273 20+273];
I=zeros(400,1);
Vi=ones(400,1);
X= [1.53 0.35 700;1 0.3 600;1.1 0.33 750];
x3=X(:,1);
x4=X(:,2);
x5=X(:,3);
for i=1:length(Tck) % I=2
    for k=1:size(X,1) %k=3
        Vt(k,i) = K.*Tck(i)/q;
        Iph(k,i)= (Isc + ki .* (Tck(i)-298)).*(G(i)./1000);
        Irs(k,i) = Isc./((exp((q.*Voc)./(x3(k,:).*Ns.*K.*Tck(i))))-1);
        Io(k,i) = Irs(k,i).* (Tck(i)./298).^3 .* exp(((q.*Ego)./(x3(k,:).*K))*(1./298 - 1./Tck(i)));
        g(k,:) = (Np.*Iph(k,i))-Io(k,i).*(exp((Vi+I.*x4(k,:))./Vt(k,i)/Ns./x3(k,:))-1)-((Vi+ I.*x4(k,:))./x5(k,:)) - I;
    end
end

Answer 1

[Voss]

clc
clear all;
% ED = readmatrix("Data filteration1.xlsx");
ki = 0.0042;    %%current temp coeff
Ns=72;          %%72cells in series and 1 in parellel
Np=1;
Ego=1.1;
K= 1.380*10^-23;
q= 1.602*10^-19;
Voc=48.37;
Isc=10.27;
G=[1000 800];
Tck = [25+273 20+273];
I=zeros(400,1);
Vi=ones(400,1);
X= [1.53 0.35 700;1 0.3 600;1.1 0.33 750];
x3=X(:,1);
x4=X(:,2);
x5=X(:,3);

nT = length(Tck);
nX = size(X,1);
g = zeros(nT*nX,numel(I));

row = 1;

for i=1:nT % I=2
    for k=1:nX %k=3
        Vt(k,i) = K.*Tck(i)/q;
        Iph(k,i)= (Isc + ki .* (Tck(i)-298)).*(G(i)./1000);
        Irs(k,i) = Isc./((exp((q.*Voc)./(x3(k,:).*Ns.*K.*Tck(i))))-1);
        Io(k,i) = Irs(k,i).* (Tck(i)./298).^3 .* exp(((q.*Ego)./(x3(k,:).*K))*(1./298 - 1./Tck(i)));
        g(row,:) = (Np.*Iph(k,i))-Io(k,i).*(exp((Vi+I.*x4(k,:))./Vt(k,i)/Ns./x3(k,:))-1)-((Vi+ I.*x4(k,:))./x5(k,:)) - I;
        row = row+1;
    end
end

size(g)

ans = 1×2

6 400

[Mitali Murkar]

Hello Voss, thank you so much for the hint. It works now! Very helpful.

[Voss]

You're welcome!

Answer 2

[the cyclist]

I'm guessing you intended

g(k,i)

rather than

g(k,:)

in the last line of the for loop.

[Mitali Murkar]

As per my understanding, the problem is not in first four lines after for loop where I used (k,i). This could give me 6 different values after solving outer and inner loop.

However, for below line:

g(k,:) = (Np.*Iph(k,i))-Io(k,i).*(exp((Vi+I.*x4(k,:))./Vt(k,i)/Ns./x3(k,:))-1)-((Vi+ I.*x4(k,:))./x5(k,:)) - I;

After running the programme, g is 3*400 matrix (because of 400 datasets of Vi and I. On other hand, I should get the output with 6*400 size matrix

[the cyclist]

I'm not certain why you think it should be 6*400. If you look at your indexing, here is what happens during all the iterations of your for loops:

i==1, k==1

Write g(1,:)

i==1, k==2

Write g(2,:)

i==1, k==3

Write g(3,:)

i==2, k==1

Over-write to g(1,:)

i==2, k==2

Over-write to g(2,:)

i==2, k==3

Over-write to g(3,:)

===========================

Notice that you never use i to index into g, so you are overwriting instead of creating rows 4-6.

[Mitali Murkar]

Thank you so much for clarification and your very prompt response.