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 > >