How to use QR decomposition to find eigenvalues?

[Hercuflea]

Homework Statement

I need to understand how I would go about using QR decomposition of a matrix to find the matrix's eigenvalues. I know how to find the factorization, just stuck on how I would use that factorization to find the eigenvalues.

Homework Equations

A=QR where Q is an orthogonal matrix such that Qtranspose = Qinverse

The Attempt at a Solution

det(λ*I - QR) = 0? this doesn't really help.

 

[SteamKing]

If you do a google search, you will find a number of different hits on this topic.

Here is one such hit: http://www.mcs.csueastbay.edu/~malek/TeX/Qr.pdf

The use of QR for finding eigenvalues is iterative, however. The values returned are approximations of the true eigenvalues.