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Computation of eigenvalues

We would like to compute the eigenvalues of the matrix

eigen1.gif

Recall that an eigenvalue is a number eigen2.gif which, together with its eigenvector eigen3.gif, solves the equation eigen4.gif. We can find eigen5.gif by solving the equation eigen6.gif. Substituting the matrix A defined above, we get

eigen7.gif

The characteristic polynomial is equivalent to the determinant of the matrix eigen8.gif.

eigen9.gif

We can compute eigen10.gif by using cofactors:

eigen11.gif

The roots of this cubic polynomial are the three eigenvalues of A:

eigen12.gif

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Created: Oct 06 1997 --- Last modified: Sat Mar 04 12:36:24 2000
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