How can I expand a array with with even zero intervals in between?

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Seba.V on 15 Aug 2019
Edited: Bruno Luong on 15 Aug 2019
Suppose I have an array a=[1 2 3], how can i generate a code that would add x-amout of zeros in between each value of the original array?
For example
a=[1 2 3] ----> function or loop (code) -----> a1=[1 0 0 2 0 0 3]

Bruno Luong on 15 Aug 2019
Edited: Bruno Luong on 15 Aug 2019
nz = 2;
b = a;
b(end+nz,:) = 0;
b = b(1:end-nz)

Seba.V on 15 Aug 2019
Thank you !
Could you please tell me how the last two line of code work though please?
Sorry i am just starting out!
Bruno Luong on 15 Aug 2019
To understand you must aware that MATLAB store array column-wise, meaning
A = [1 3 5;
2 4 6];
is stored in contiguous internally 1, 2, 3, 4, 5 6, and when you RESHAPE A by
A(1:4), you'll get a row vector [1 2 3 4].
Now with that in mind, this first statement add nnz rows of zeros in B, so after reshaping you'll get NNZ zeros in between elements of the first row.
The last statement also removes the last NNZ zeros after the last element of a.