Matrices for Engineers

If complex eigenvalues occur, they must occur in complex conjugate pairs. The procedure for finding the eigenvectors follows that of Sections 7.8 and 7.9.
The matrix
has a characteristic matrix
and a characteristic polynomial
The three eigenvalues are
The eigenvectors are obtained by putting each eigenvalue in turn into
For ? 1 = ?1
This can be expanded to yield the linearly independent system
and the solution here is
and
Thus, with an arbitrary selection of x 2 = 1, the first eigenvector is
For ? 2 = ?1 + i2,
and when this matrix representation is expanded it is observed that
Here
and
so that with the arbitrary selection of x 2 = 5, the second eigenvector is
Finally, for ?3 = ?1 ? i2
or in expanded form
Here
and
so that with the arbitrary selection of x 2 = 5, the third eigenvector becomes
The reader may verify that the three eigenvectors form a linearly independent set.