MATLAB Answers


Produce matrices through for loop

Asked by Ali Esmaeilpour on 27 May 2019
Latest activity Commented on by Ali Esmaeilpour on 31 May 2019
Hello people! I want to produce N number of matrices while k=1:N and I want the result in a way like h(k). I mean h(1),h(2) etc which are matrices that depend on k. I mean creating them through a for loop. I tried the following code but it failed to produce N matrices and it just gave one matrix:
close all;
hx = [-1/sqrt(5);-2/sqrt(5)];
hu = [0;0];
N = 25;
Ek1 = zeros(N+1,1);
Ek2 = ones(N+1,1);
Ek3 = ones(N,1);
Ek4 = zeros(N,1);
h = zeros(102,1);
for k=1:N
if k==1
h(:,:) = [kron(Ek2,hx);kron(Ek3,hu)];
h(:,:) = [kron(Ek1,hx);kron(Ek4,hu)];

  1 Comment

" I want to produce N number of matrices..."
Then the best** solution is to use indexing, exactly as your question already shows
** best in the sense simplest, neatest, easiest to write, easiest to debug, and most efficient.
Note that dynamically access variable names is one way that beginners force themselves into writing slow, complex, buggy code that is hard to debug. Read this to know why:

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1 Answer

Answer by Geoff Hayes
on 27 May 2019
 Accepted Answer

Ali - if the output matrix of each iteration is of dimension 102x1, then you could store each output as a column in a 102xN matrix. For example,
h = zeros(102,N);
for k=1:N
if k==1
h(:,k) = [kron(Ek2,hx);kron(Ek3,hu)];
h(:,k) = [kron(Ek1,hx);kron(Ek4,hu)];


N can be 5 or 10 or 15 or 20 or 25
Geoff Hayes
on 31 May 2019
For the case where N is 5, then
h = zeros((2*N + 1) * size(hx,1), N);
h is a 22x5 array. Is this correct?
yeah tnx my friend i debugged that main code and solve it with sedumi. tnx again for you consideration. cheers!

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