preserving order of eigenvalues in a matrix diagonalization

• To: mathgroup at smc.vnet.net
• Subject: [mg61819] preserving order of eigenvalues in a matrix diagonalization
• From: grub_snuffler at yahoo.com
• Date: Mon, 31 Oct 2005 01:17:12 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```I'm trying to diagonalize a matrix in Mathematica, but I need the eigenvalues
to stay in order.  So, for instance, for the initial matrix m,

m = {{2, 0}, {0, 3}}

some function, say "diagonalize[m]", should just return m.

If I use

diagonalize[m_] := Transpose[Eigenvectors[m]].m.Eigenvectors[m]

it returns {{3, 0}, {0, 2}}.    I can certainly write my own routine by
hand, but I thought I'd ask if there's an easy way to ask Mathematica to
preserve the order.

Thanks,
john

```

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