# Discrete Fourier Transform Matrix (DFT)

When does it occur that the eigenvalues of a Discrete Fourier Transform matrix are distinct?

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The eigenvalues of the DFT matrix are treated here. They are distinct for $n<4$; for $n=4$ the eigenvalue $1$ is double and beginning with $n=9$ all four eigenvalues are multiple.

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Thanks for the information. What is about n=5, 6,7, 8? –  user12290 Jul 3 '11 at 4:55
@user12290: It's all right there in the article I linked to. –  joriki Jul 3 '11 at 8:29