[petsc-users] SLEPc EPSGD: Can not converge, error estimation floats over 1e-6

[Runfeng Jin]

Thank you, I will have a try to them.

I use JD and GD because this matrix is about quantum chemical computing,
and it has the property that diagonal elements dominate. This property
seems to be suitable for JG and GD.

> JD and GD are best when you need to compute eigenvalues around a target
About this, I want to compute only three smallest real eigenvalues, should
this be the situation suitable for GD and JD？

Runfeng

Jose E. Roman <jroman at dsic.upv.es> 于2022年7月13日周三 12:36写道：

> Does it work with -eps_gd_blocksize 1 ?
> Why do you want to use GD? JD and GD are best when you need to compute
> eigenvalues around a target. For your case, I would try with the default
> solver (Krylov-Schur) or with LOBPCG.
>
> Jose
>
>
> > El 13 jul 2022, a las 4:59, Runfeng Jin <jsfaraway at gmail.com> escribió:
> >
> > Hi!
> > I am trying to find 3 eigenvalues of a matrix 81,160*81,160, and it get
> 0 eigenvalue after  162320 iterations. I use -eps_monitor and find error
> estimation floats over 1e-6, I didn't set the tolerance so it should be the
> default 1e-8. Actually it should achieve 1e-10.
> >
> > I have tried  JD and GD, both of them can not converge. Does there any
> ways to help it converge to the 1e-10?
> >
> > By the way, I use default Convergence criterion, the output of
> -log_view and -eps_monitor  are shown in attachment.
> > Thank you!
> >
> > Runfeng Jin
> > <eps_monitor-and-log_view.txt>
>
>
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