Hi Mark,
Thanks for your help! It clears many of my doubts.
Thanks,
Feng
From: Mark Adams
Sent: 05 October 2022 15:05
To: feng wang
Cc: petsc-users@mcs.anl.gov
Subject: Re: [petsc-users] clarification on extreme eigenvalues from
KSPComputeEigenvalues
On
These seem to be sorted. You can also ask for "Extreme" eigenvalues and
just get these two that you can use for the condition number estimate. That
is the most common use.
Mark
>
>-
>
> Thanks for your help and sorry for so many questions,
> Feng
>
>
>
>
t; and which ones
are the "highest"?
Thanks for your help and sorry for so many questions,
Feng
From: Mark Adams
Sent: 04 October 2022 17:18
To: feng wang
Cc: petsc-users@mcs.anl.gov
Subject: Re: [petsc-users] clarification on extreme eigenva
The extreme eigenvalues are the lowest and highest.
A perfect preconditioner would give all eigenvalues = 1.0
Mark
On Tue, Oct 4, 2022 at 1:03 PM feng wang wrote:
> Dear All,
>
> I am using the KSPComputeEigenvalues to understand the performance of my
> preconditioner, and I am using the right-
Dear All,
I am using the KSPComputeEigenvalues to understand the performance of my
preconditioner, and I am using the right-preconditioned GMRES with ASM. In the
user guide, it says this routine computes the extreme eigenvalues of the
preconditioned operator. If I understand it correctly, these
