Re: Eigenvalue Problem
- To: mathgroup at smc.vnet.net
- Subject: [mg16952] Re: Eigenvalue Problem
- From: Pierre infelta <pierre.infelta at epfl.ch>
- Date: Thu, 8 Apr 1999 02:32:47 -0400
- Organization: EPFL
- References: <7e9odu$3km@smc.vnet.net> <7ef0d5$c4f$4@dragonfly.wolfram.com>
- Sender: owner-wri-mathgroup at wolfram.com
try
Needs["Miscellaneous`RealOnly`"]
m = {{10 A, 0, B, 0, 0, 0},
{0, -2 A, 0, C, 0, 0},
{B, 0, -8 A, 0, C, 0},
{0, C, 0, -8 A, 0, B},
{0, 0, C, 0, -2 A, 0},
{0, 0, 0, B, 0, 10 A}}
The answer replaces the nonreal roots by nonreal.
Ed McBride wrote:
>
> > I am trying to solve the eigenvalue problem for the following matrix:
> >
> > m = {{10 A, 0, B, 0, 0, 0},
> > {0, -2 A, 0, C, 0, 0},
> > {B, 0, -8 A, 0, C, 0},
> > {0, C, 0, -8 A, 0, B},
> > {0, 0, C, 0, -2 A, 0},
> > {0, 0, 0, B, 0, 10 A}}
> >
> > which is symmetric. Now mathematica returns some complex eigenvalues
> > which is not
> > possible for a real, symmetric matrix. Can anybody help me ?
>
> I get the same phenomenon. And I also got it with a 3 x 3 I made up. I
> presume the results turn out to be real if a,b,c are real, but they are
> too complicated to prove this without a bunch of work. Sorry, Ed
> McBride