How to extract a period of history of a signal in simulink?

I would like to extract a period of history of a signal in simulink. Say, I have a discrete sampled signal 'u', the task is to retrieve the vector [u(k-1), u(k-2), ..., u(k-N)], where each 'k' represents the signal at each sampled time. When k<N+1, we set the elements at k:N as zeros since there is no definition of the signal before the starting time. I have a simple M-file that can do the job (see the following code), but I feel puzzled to implement this functionality in simulink. The input variable 'u' in the M-file is the measured signal that I want to create a buffer zone to store the period from u(k-1) backward to u(k-N). Can anyone give me a hint on this, thanks a million.

      function hist = extract_hist(u, k, N)
      % -------------------------------------------------------------------------
      % Extract a period of history of a signal 'u' at a given discrete moment
      % 'k'. The output stores the history from u(k-1) to u(k-N) in a stack form.
      % For the discrete moments before (N+1), elements from k:N are zeros. The
      % input signal 'u' shall be an ongoing growing vector in simulink.
      % -------------------------------------------------------------------------
      hist = zeros(N,1);
      if k >= N+1
          hist = u(k-1:-1:k-N);
      elseif k > 1 && k < N+1
          hist(1:k-1) = u(1:k-1);
      end

Answer 1

[ES]

You can use a group of Unit Delay Blocks to do the same. That precisely does what you want.

[Fu-Rui Xiong]

Indeed, this is a solution, but when the history extraction turns out longer, say, I wanna extract 45 historical moments from u(k-45) to u(k-1), it must be a tedious job to pile all those modules in a model. Is there a way to vectorize the block like unit delay? Or how can I integrate the M-file I wrote to a simulink model? I feel puzzle because the signal itself is growing during the measuring process. Thanks anyway Chocolate.

[ES]

You need this, use a MATLAB Fcn Block and place your code inside.

http://www.mathworks.in/help/simulink/ug/creating-an-example-model-that-uses-a-matlab-function-block.html

[Fu-Rui Xiong]

Thanks buddy, I'll try it out.