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Re: Issues with eigs


From: Thomas D. Dean
Subject: Re: Issues with eigs
Date: Fri, 7 Sep 2018 09:13:39 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1

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







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