Re: variability in a test for eigs.cc

[David Bateman]

Ben Abbott wrote:
> On Mar 28, 2010, at 4:07 PM, Michael D Godfrey wrote:
>
>   
> > On 03/28/2010 12:42 PM, Ben Abbott wrote:
> >     
> > > Thanks. Perhaps the right thing to do is to loop through the test 3 times and 
> > > check that at least one result is less than 1e-11.
> > >
> > > If there is no objection, I'll try to push that change later today.
> > >
> > > Ben
> > >   
> > >       
> > I think it would be a good idea to let whoever has had responsibility
> > for this algorithm to take a look and determine a few things like: what
> > inputs produce largest errors and can anything be done about improving
> > accuracy.
> >
> > Michael
> >     
>
> ok. It looks to me like David introduced these tests.
>
> I've cc'd him.
>
> David, do you have any suggestion for how to deal with the variability in the 
> eigs.cc test?
>
> The start of this thread is at the link below.
>
>         
> https://www-old.cae.wisc.edu/pipermail/octave-maintainers/2010-March/015680.html
>
> Ben
>
>   
This test as you've written it shouldn't use 'li'. The matrix is 
hermitian and the eigenvalues as real and so looking for the largest 
imaginary part of the eigenvalues will just give you noise. You should 
use 'lr' instead in this case.

D.