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MathGroup Archive 2005

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Re: Eigensystem Bug? OS-X

  • To: mathgroup at smc.vnet.net
  • Subject: [mg56132] Re: Eigensystem Bug? OS-X
  • From: Peter Pein <petsie at arcor.de>
  • Date: Sat, 16 Apr 2005 03:52:25 -0400 (EDT)
  • References: <d3o0f3$bnc$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Only a guess, because I've got a windows-pc:

What happens if you try Eigenvectors[Rationalize@mat] ?

Erich Mueller wrote:
> I have some strange behavior of Eigensystem and Eigenvectors [but not 
> Eigenvalues] on my G5 running OS-X 10.3.8, and Mathematica 5.1.0.0.
> 
> The Kernel Hangs when I try to calculate the Eigenvectors of the 18x18 
> Matrix at the end of this message. [Its the smallest matrix for which I 
> have the problem.]  It does not respond to an "Abort Evaluation", or 
> "Interupt Evaluation Signal", and I must kill it from the terminal.
> 
> There is no problem finding the eigenvalues of this same matrix on a PC. 
>   Is there someone who can suggest a fix/workaround?  Failing that, is 
> there anyone with a mac who can verify the problem?
> 
> Thanks,
> Erich
> 
> 
> {{-4., 1., 1., 1., 0., 0., 1., 0., 0., 0., 0. + 1.*I, 0. + 1.*I, 0. - 
> 1.*I, 0., 0., 0. - 1.*I, 0., 0.},
>   {1., -4., 1., 0., 1., 0., 0., 1., 0., 0. + 1.*I, 0., 0. + 1.*I, 0., 0. 
> - 1.*I, 0., 0., 0. - 1.*I, 0.},
>   {1., 1., -4., 0., 0., 1., 0., 0., 1., 0. + 1.*I, 0. + 1.*I, 0., 0., 
> 0., 0. - 1.*I, 0., 0., 0. - 1.*I},
>   {1., 0., 0., -4., 1., 1., 1., 0., 0., 0. - 1.*I, 0., 0., 0., 0. + 
> 1.*I, 0. + 1.*I, 0. - 1.*I, 0., 0.},
>   {0., 1., 0., 1., -4., 1., 0., 1., 0., 0., 0. - 1.*I, 0., 0. + 1.*I, 
> 0., 0. + 1.*I, 0., 0. - 1.*I, 0.},
>   {0., 0., 1., 1., 1., -4., 0., 0., 1., 0., 0., 0. - 1.*I, 0. + 1.*I, 0. 
> + 1.*I, 0., 0., 0., 0. - 1.*I},
>   {1., 0., 0., 1., 0., 0., -4., 1., 1., 0. - 1.*I, 0., 0., 0. - 1.*I, 
> 0., 0., 0., 0. + 1.*I, 0. + 1.*I},
>   {0., 1., 0., 0., 1., 0., 1., -4., 1., 0., 0. - 1.*I, 0., 0., 0. - 
> 1.*I, 0., 0. + 1.*I, 0., 0. + 1.*I},
>   {0., 0., 1., 0., 0., 1., 1., 1., -4., 0., 0., 0. - 1.*I, 0., 0., 0. - 
> 1.*I, 0. + 1.*I, 0. + 1.*I, 0.},
>   {0., 0. - 1.*I, 0. - 1.*I, 0. + 1.*I, 0., 0., 0. + 1.*I, 0., 0., 4., 
> -1., -1., -1., 0., 0., -1., 0., 0.},
>   {0. - 1.*I, 0., 0. - 1.*I, 0., 0. + 1.*I, 0., 0., 0. + 1.*I, 0., -1., 
> 4., -1., 0., -1., 0., 0., -1., 0.},
>   {0. - 1.*I, 0. - 1.*I, 0., 0., 0., 0. + 1.*I, 0., 0., 0. + 1.*I, -1., 
> -1., 4., 0., 0., -1., 0., 0., -1.},
>   {0. + 1.*I, 0., 0., 0., 0. - 1.*I, 0. - 1.*I, 0. + 1.*I, 0., 0., -1., 
> 0., 0., 4., -1., -1., -1., 0., 0.},
>   {0., 0. + 1.*I, 0., 0. - 1.*I, 0., 0. - 1.*I, 0., 0. + 1.*I, 0., 0., 
> -1., 0., -1., 4., -1., 0., -1., 0.},
>   {0., 0., 0. + 1.*I, 0. - 1.*I, 0. - 1.*I, 0., 0., 0., 0. + 1.*I, 0., 
> 0., -1., -1., -1., 4., 0., 0., -1.},
>   {0. + 1.*I, 0., 0., 0. + 1.*I, 0., 0., 0., 0. - 1.*I, 0. - 1.*I, -1., 
> 0., 0., -1., 0., 0., 4., -1., -1.},
>   {0., 0. + 1.*I, 0., 0., 0. + 1.*I, 0., 0. - 1.*I, 0., 0. - 1.*I, 0., 
> -1., 0., 0., -1., 0., -1., 4., -1.},
>   {0., 0., 0. + 1.*I, 0., 0., 0. + 1.*I, 0. - 1.*I, 0. - 1.*I, 0., 0., 
> 0., -1., 0., 0., -1., -1., -1., 4.}}
> 
-- 
Peter Pein
Berlin


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