tridiagonal array in matlab

main.m
n = 5; % size of array
a = randn(1, n); % values on main diagonal
b = randn(1, n-1); % values on upper diagonal
c = randn(1, n-1); % values on lower diagonal
A = spdiags([c; a; b], -1:1, n, n); % create tridiagonal array
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main.m
% solve the system Ax = d
d = randn(n, 1); % right-hand side vector
c = [c, 0]; % append 0 to lower diagonal
b = [b, 0]; % append 0 to upper diagonal
x = zeros(n, 1); % initialize solution vector
% forward elimination
for k = 2:n
    m = c(k) / a(k-1);
    a(k) = a(k) - m*b(k-1);
    d(k) = d(k) - m*d(k-1);
end
% back substitution
x(n) = d(n) / a(n);
for k = n-1:-1:1
    x(k) = (d(k) - b(k)*x(k+1)) / a(k);
end
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