Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2008

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Help with minimization of Eigenvalues

  • To: mathgroup at smc.vnet.net
  • Subject: [mg87761] Re: Help with minimization of Eigenvalues
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 16 Apr 2008 07:14:11 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <fu4ll6$sfq$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de

Hi,

Eig[a_?NumericQ, b_?NumericQ] := With[{m = {{a, b}, {b, -a + 1}},
    s = {{1, 0}, {0, 3 a}}},
   Eigenvalues[N[{m, s}]] // First
   ]

may help.

Regards
   Jens

Chimico wrote:
> Hi,
> 
> I am trying to minimize a particular eigenvalue of a generalized
> eigenvalue problem that depends on a few parameters. I have the
> following problem:
> 
> Suppose we have two matrices s and m like these (the real matrices are
> much more complicated)
> 
> m = {{a, b}, {b, -a + 1}}
> 
> s = {{1, 0}, {0, 3a}}
> 
> If I define the function Eig
> 
> Eig[a_, b_] := Eigenvalues[{m, s}]//First
> 
> And use it with the FindMinimum function it does not work.
> Infact just calling
> 
> Eig[1,2] gives the error
> 
> Eigenvalues::gfargs:
>    Generalized Eigenvalues
>      arguments accept only matrices with machine real
>       and complex elements. More...
> 
> Even inserting Evaluate[] into the Eigenvalues function does not work.
> What am I doing wrong?
> Any help would be appreciated :-)
> thanks  Dario
> 
> 


  • Prev by Date: Re: mx files
  • Next by Date: Re: Select from list
  • Previous by thread: Help with minimization of Eigenvalues
  • Next by thread: Re: Help with minimization of Eigenvalues