MATLAB: Scalar to vector formation, k = [k1 k2 k3 k4] to [k1,-k1,0,​0:-k1,k1+k​2,-k2,0:0,​-k2,k2+k3,​0:0,0,-k3,​k3+k4]

Question

Answer 1

k = [0.6337,0.6337,0.6337,0.6337];
n = numel(k);
m = zeros(n);
m(2:n+1:end-n) = 0-k(1:end-1);  % lower
m(1+n:n+1:end) = 0-k(1:end-1);  % upper
m(1:n+1:end) = [0,k(1:end-1)]+k % main

Giving:

m =
   0.63370  -0.63370   0.00000   0.00000
  -0.63370   1.26740  -0.63370   0.00000
   0.00000  -0.63370   1.26740  -0.63370
   0.00000   0.00000  -0.63370   1.26740