Formula and code for energy spectrum is wrong

[rshayduk]

should be replaced by E_i=(Ai^2+Bi^2)Wi^2mi, in which mi=Xi_tMXi, in which Xi is the ith eigenvector, and M is the mass matrix and _t stands for the transpose. In other words, Xi_tMXi is matrix notation of the scalar product of the two vectors, Xi and MXi, i.e. Xi.MXi.

[dschick]

thanks @rshayduk for pointing this out

you are referring to this line of code
E[i, :] = 0.5 * (A[i, :].T**2 + B[i, :].T**2) * omega**2 * masses * np.sum(Xi**2, 0).T
so the correct form would be:
E[i, :] = (A[i, :].T**2 + B[i, :].T**2) * omega**2 * Xi.T*masses*Xi

[rshayduk]

I am not sure I understand. Is Xi the i-th eigenvector or a matrix?