A = [1 2; 2 4]

% Compute the determinat
det(A)

% Compute the eigenvalues
eig(A)

% Compute eigenvalues and (normalized) eigenvectors
[V, L] = eig(A)

[1/sqrt(5), 2/sqrt(5)]'

% Exercise (*)
A = [0 2 -1/2; 2 0 -3; -1/2 -3 0]
eig(A)