how to Assemble this matrix

[John D'Errico]

Please stop asking the same question. Why was the first answer not adequate in your other question? There you were told how to create that exact matrix.

[Stephen23]

The original question, with very compact solution:

http://www.mathworks.com/matlabcentral/answers/265485-how-to-assemble-the-matrix-shown-in-the-image-on-matlab-for-any-number-of-nodes

[Rena Berman]

(Answers dev) Restored question.

Answer 1

[Walter Roberson]

n = 4;    %for example

main_diagonal = [ [-4, repmat(-3,1,n-2), -4], repmat([-5, repmat(-4,1,n-2), -5], 1, 2), [-6, repmat(-5,1,n-2), -6] ];
N = length(main_diagonal);

m = diag(ones(1, N-4), -4) +
    diag(ones(1, N-1), -1) +
    diag(main_diagonal) +
    diag(ones(1, N-1), 1) +
    diag(ones(1, N-4), -4)