MATLAB: Create a function that takes a vector as an input parameter and returns another vector where each component is the initial vector repeated n times.

Question

create a function that takes a vector as an input parameter and returns another vector where each component is the initial vector repeated n times.

I have thought about doing the following:

function B = cyclic_shift_recursion(A,n) %n is the number of times the vector is repeated and A is the vector that I want to repeat
if n<=0
    return
else 
B=[A cyclic_shift_recursion(A,n-1)];
end
end

I get an error and I do not understand why, how can I correct this? Is there another easy way to do this? Thank you.

Answer 1

"Output argument "B" (and maybe others) not assigned during call to "cyclic_shift_recursion"

Well, yes matlab is correct. Your code:

function B = cyclic_shift_recursion(A,n) %n is the number of times the vector is repeated and A is the vector that I want to repeat
if n<=0
    return
%... rest doesn't matter

So for n = 0, the function returns immediately, without assigning anything to B.

Simply assign something to B before returning. As it's homework, I'm not going to tell you what to assign, but it's very trivial.

As to your question:

" But how can I do a function that does this without using repmat"

There's all sort of ways you could cheat, avoiding repmat while not adhering to the spirit of your assignment (which it seems is to use recursion). E.g.:

kron(ones(1, n), A)

reshape(repelem(A(:),1, n), 1, [])

A(reshape((1:numel(A))' + zeros(1, n), 1, []))

and probably more...