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

[Runfeng Jin]

Ok!  I will try it.

Runfeng

Jose E. Roman <jroman at dsic.upv.es> 于2022年7月13日周三 14:10写道：

>
>
> > El 13 jul 2022, a las 7:59, Runfeng Jin <jsfaraway at gmail.com> escribió:
> >
> > 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.
>
> This is useful if you want to use a diagonal preconditioner (classical
> Davidson), but generalized Davidson can take any preconditioner. In PETSc
> the default preconditioner is not Jacobi but Block Jacobi+ILU.
>
> >
> > > 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？
>
> No, try Krylov-Schur or LOBPCG.
>
> >
> > 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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