How can I create create a matrix with a pattern?

Hi,

I have a matrix S (4x12) like this:

S = [0 0 2 0 0 0 2 0 0 0 2 0;
     0 0 0 2 0 0 0 2 0 0 0 2;
     2 0 0 0 2 0 0 0 2 0 0 0;
     0 2 0 0 0 2 0 0 0 2 0 0]

I need to create a matrix Z that is 4x27 and contains the original pattern from S in its first 12 columns and continues the pattern up to column 27.

Any help would be greatly appreciated.

Answer 1

[Image Analyst]

Try this:

z = repmat(S, [1, 3]); % Replicate S
z =z(:, 1:27) % Extract only the 27 columns that are needed.

[John Smith]

Thanks for the answer! This is great!

[John Smith]

What exactly does the "[1, 3]" in repmat do?

[Image Analyst]

It tells repmat() how many copies to make in the rows (vertical) direction and columns (horizontal) direction. So it takes S and copies it once in the vertical direction (not an additional copy, just the one original matrix), and makes 3 copies in the horizontal direction. So in the end you have 3 copies side-by-side. Now since S was 12 wide to start, you'll end up with a 36 column wide matrix. That's why I had to crop off anything beyond 27 columns which is all you wanted.