How to calculate eigenvalues using QR method?

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How can I get eigenvalues of matrix using Apache Commons Math? I know there is 2 classes EigenDecomposition and QRDecomposition, but how to combine them to get eigenvalues?

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duffymo On

Why combine them? QR can give you eigenvalues:

http://en.wikipedia.org/wiki/QR_algorithm

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apete On

You seem to confuse the QR decomposition with the QR eigenvalue algorithm.

The QR decomposition cannot give you the eigenvalues of a matrix, but it can be used as a component to a more complex algorithm that produce eigenvalues and eigenvectors.

http://en.wikipedia.org/wiki/QR_algorithm

http://en.wikipedia.org/wiki/QR_decomposition