5
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Let's consider the simple code

Eigenvalues[{{a, b, c}, {d, e, f}, {g, h, i}}, Cubics -> True]
(* {Root[<<1>> &, 1],Root[<<1>> &, 2],Root[<<1>> &, 3]} *)

Using the option Cubics -> True, I expected the Root[] expressed in terms of radicals. Why it's not the case?

The same happens considering a 4 by 4 matrix and the option Quartics -> True.

P. S. I know that I can use ToRadicals but my question is about the options Cubics and Quartics that seem do not have any effect for Eigenvalues.

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  • $\begingroup$ What version are you on? Eigenvalues[{{a, b, c}, {d, e, f}, {g, h, i}}, Cubics -> True] yields explicit radicals in 11.2. $\endgroup$ – J. M. is away Nov 1 '17 at 9:37
  • $\begingroup$ I'm using version 11.2 on Linux x86 $\endgroup$ – Giancarlo Nov 1 '17 at 9:39
  • 5
    $\begingroup$ Weird. It happens on a 32-bit kernel but not 64. I'll report it as a bug. $\endgroup$ – Daniel Lichtblau Nov 1 '17 at 15:36
  • $\begingroup$ Works on Raspberry Pi too (v11.0.1, 32-bit, ARM) $\endgroup$ – Szabolcs Nov 2 '17 at 8:13

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