MATLAB: Code to generate matrix

matrix

bold Hello,
I have this matrix, can someone please adv how to write the code:
A = [ 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0;
     -1 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0;
    0  -1 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0 0 0 0 0 0;
    0 0  -1 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0 0 0 0 0;
    0 0 0  -1 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0 0 0 0;
    0 0 0 0  -1 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0 0 0;
    0 0 0 0 0  -1 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0 0;
    0 0 0 0 0 0  -1 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0 0 0;
    0 0 0 0 0 0 0  -1 5 0  0 0 0 0 0 0 0   -1  0 0 0 0 0 0 0 0;
    -1 0 0 0 0 0 0 0  0 4 -1  0 0 0 0 0 0 0  -1  0 0 0 0 0 0 0;
    0 -1 0 0 0 0 0 0 0  -1 4 -1  0 0 0 0 0 0 0 -1  0 0 0 0 0 0;
    0 0 -1 0 0 0 0 0 0 0  -1 4 -1 0 0 0 0 0 0 0 -1   0 0 0 0 0;
    0 0 0 -1 0 0 0 0 0 0 0  -1 4 -1 0 0 0 0 0 0 0 -1   0 0 0 0;
    0 0 0 0 -1 0 0 0 0 0 0 0  -1 4 -1 0 0 0 0 0 0 0 -1   0 0 0;
    0 0 0 0 0 -1 0 0 0 0 0 0 0  -1 4 -1 0 0 0 0 0 0 0 -1   0 0;
    0 0 0 0 0 0 -1 0 0 0 0 0 0 0  -1 4 -1 0 0 0 0 0 0 0 -1   0;
    0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0  -1 4 -1 0 0 0 0 0 0 0 -1  ;
    0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0  -1 5     0 0 0 0 0 0 0 0;
    0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0   0 3 -1    0 0 0 0 0 0;
    0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0  0  -1 3 -1    0 0 0 0 0;
    0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0  0   -1 3 -1    0 0 0 0;
    0 0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0  0   -1 3 -1    0 0 0;
    0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0  0    -1 3 -1   0 0;
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0  0    -1 3 -1   0;
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0  0     -1 3 -1 ;
    0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0  0     -1 3   ];
b=[0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;5;0;0;0;0;0;0;0;5];

Best Answer

You can put it together using diag()
d0 = [repmat(4,1,8), 5, repmat(4,1,8), 5, repmat(3,1,8)];
d1 = ones(1, length(d0)-1);
d9 = ones(1, length(d0)-9);
A = diag(d0,0) + diag(d1, -1) + diag(d1, 1) + diag(d9, -9) + diag(d9, 9);
b = [zeros(1,17), 5, zeros(1, 7), 5];
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