at-Sea-March-29-Rotterdam.htm
>
>
> From: Barry Smith <bsm...@mcs.anl.gov>
> Sent: Saturday, March 25, 2017 1:29 AM
> To: Klaij, Christiaan
> Cc: Lawrence Mitchell; Matthew Knepley; petsc-users@mcs.anl.gov
> Subject: Re: [petsc
-Rotterdam.htm
From: Barry Smith <bsm...@mcs.anl.gov>
Sent: Saturday, March 25, 2017 1:29 AM
To: Klaij, Christiaan
Cc: Lawrence Mitchell; Matthew Knepley; petsc-users@mcs.anl.gov
Subject: Re: [petsc-users] left and right preconditioning with a constant null
space
>
constant null space.
>
> Chris
>
> From: Klaij, Christiaan
> Sent: Friday, March 24, 2017 9:05 AM
> To: Lawrence Mitchell; Matthew Knepley
> Cc: petsc-users@mcs.anl.gov
> Subject: Re: [petsc-users] left and right preconditioning w
On Fri, Mar 24, 2017 at 10:17 AM, Lawrence Mitchell <
lawrence.mitch...@imperial.ac.uk> wrote:
>
> > On 24 Mar 2017, at 15:11, Klaij, Christiaan wrote:
> >
> > I've written a small PETSc program that loads the four blocks,
> > constructs Sp, attaches the null space and solves
> On 24 Mar 2017, at 15:11, Klaij, Christiaan wrote:
>
> I've written a small PETSc program that loads the four blocks,
> constructs Sp, attaches the null space and solves with a random
> rhs vector.
>
> This small program replicates the same behaviour as the real
> code:
24, 2017 1:34 PM
To: Lawrence Mitchell; Matthew Knepley
Cc: petsc-users@mcs.anl.gov
Subject: Re: [petsc-users] left and right preconditioning with a constant null
space
I've also loaded the four blocks into matlab, computed
Sp = A11 - A10 inv(diag(A00)) A01
and confirmed that Sp has indeed a
From: Lawrence Mitchell <lawrence.mitch...@imperial.ac.uk>
Sent: Thursday, March 23, 2017 4:52 PM
To: Klaij, Christiaan; Matthew Knepley
Cc: petsc-users@mcs.anl.gov
Subject: Re: [petsc-users] left and right preconditioning with a constant null
space
On 23/03/17 15:37, Klaij, Christiaan wrote:
> Ye
On 23/03/17 15:37, Klaij, Christiaan wrote:
> Yes, that's clearer, thanks! I do have is0 and is1 so I can try
> PetscObjectCompose and let you know.
>
> Note though that the viewer reports that both S and A11 have a
> null space attached... My matrix is a matnest and I've attached a
> null
list-Human-Performance.htm
From: Lawrence Mitchell <lawrence.mitch...@imperial.ac.uk>
Sent: Thursday, March 23, 2017 11:57 AM
To: Klaij, Christiaan; Matthew Knepley
Cc: petsc-users@mcs.anl.gov
Subject: Re: [petsc-users] left and right preco
On 23/03/17 08:42, Klaij, Christiaan wrote:
> Matt, Lawrence
>
>
> The same problem happens when using gmres with rtol 1e-6 in the
> schur complement (attachment "left_schur"). I'm not sure what
> this tells us. If I understand Lawrence correctly, the null space
> may be attached to the wrong
> On 22 Mar 2017, at 16:39, Matthew Knepley wrote:
>
> Hmm, I wonder if the problem is that A11 has the nullspace, but the PC pmat
> is actually B^T diag(A)^{-1} B. I have
> to look where the solver is actually taking the nullspace from. We need to
> improve the -ksp_view
htm>
>
> --
> *From:* Matthew Knepley <knep...@gmail.com>
> *Sent:* Wednesday, March 22, 2017 4:47 PM
> *To:* Klaij, Christiaan
> *Cc:* petsc-users@mcs.anl.gov
> *Subject:* Re: [petsc-users] left and right preconditioning with a
>
nghai for the first time, March
28<http://www.marin.nl/web/News/News-items/Software-seminar-in-Shanghai-for-the-first-time-March-28.htm>
From: Matthew Knepley <knep...@gmail.com>
Sent: Wednesday, March 22, 2017 4:47 PM
To: Klaij, Christiaan
Cc: petsc-users@m
On Wed, Mar 22, 2017 at 2:58 PM, Klaij, Christiaan wrote:
> I'm solving the Navier-Stokes equations using PCFieldSplit type
> Schur and Selfp. This particular case has only Neumann conditions
> for the pressure field.
>
> With left preconditioning and no nullspace, I see that
I'm solving the Navier-Stokes equations using PCFieldSplit type
Schur and Selfp. This particular case has only Neumann conditions
for the pressure field.
With left preconditioning and no nullspace, I see that the KSP
solver for S does not converge (attachment "left_nonullsp") in
either norm.
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