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Eigenvalue Question

  1. Oct 19, 2007 #1
    Im working with Comsol and doing some eigenvalue analysis.
    Why is sometimes the eigenvalues are complex numbers and not real number frequencies?
    How should I interpret these complex eigenvalues?
  2. jcsd
  3. Oct 19, 2007 #2


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    Science Advisor

    They are sometimes imaginary because, at the heart of eigenvalue solving (the ones that I know of anyways) is solving a polynomial for it's roots. For example, finding the principal stresses in a 3x3 stress tensor is an eigenvalue problem. In that you are solving for the roots of a third order polynomial.
  4. Oct 19, 2007 #3
    okaay great, so can i just take the absolute value as the eigenfrequency to work with?
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