Re: Issues with eigs

[Thomas D. Dean]

I get different results with 5.0.0

octave:627> eigs(m1,m0)
ans =

        -0.00018 - 2672287.08391i
        -0.00018 + 2672287.08391i
         0.00027 + 2639894.41870i
         0.00027 - 2639894.41870i
        -0.00024 - 2587680.34565i
        -0.00024 + 2587680.34565i

octave:628> version
ans = 5.0.0
octave:629> which eigs
'eigs' is a function from the file
/usr/local/share/octave/5.0.0/m/sparse/eigs.m

Tom Dean

On 09/07/18 06:13, Juan Pablo Carbajal wrote:
> Hi,
>
> I can't reproduce in 4.4.0, which Octave version are you using? What OS?
>
> > eigs(m1,m0)
> ans =
>
>           0.00032 - 2672312.38464i
>           0.00032 + 2672312.38464i
>           0.00004 - 2639857.10699i
>           0.00004 + 2639857.10699i
>           0.00010 + 2587664.34543i
>           0.00010 - 2587664.34543i
>
> > version
> ans = 4.4.0
> > which eigs
> 'eigs' is a function from the file /usr/local/share/octave/4.4.0/m/sparse/eigs.m
>
> On Fri, Sep 7, 2018 at 3:02 PM Manav Bhatia <address@hidden> wrote:
> > Hi,
> >
> >     I have a set of matrices, M0 and M1 (attached), obtained from numerical 
> > discretization of a beam problem.
> >
> >     I am attempting to solve the eigenproblem    M1 x = lambda M0 x .
> >
> >     Computing this with the following works fine:
> > >   m0 = load(‘M0.txt’); m1 = load(‘M1.txt’);
> > >   eig( m1, m0)
> >
> >
> >      However, using eigs( m1, m0) throws the following error:
> > error: __eigs__: eigs: error -8 in dnaupd
> > error: called from
> >      eigs at line 285 column 18
> >
> >      I am not sure what could be causing this. Any guidance will be appreciated.
> >
> > Thanks,
> > Manav