On Mon, May 2, 2022 at 3:09 PM Amneet Bhalla wrote:
>
> While trying to use -fp_trap with a debugger on a local system we used the
> debug build of our and PETSc code and all solvers are working fine (left
> and right PC and fgmres also) and no NaNs either.
>
Debugging code tends to initial all
While trying to use -fp_trap with a debugger on a local system we used the
debug build of our and PETSc code and all solvers are working fine (left
and right PC and fgmres also) and no NaNs either. Interrogating the
optimized version of the code now…
On Mon, May 2, 2022 at 11:11 AM Matthew
On Mon, May 2, 2022 at 1:56 PM Amneet Bhalla wrote:
> Thanks Matt and Barry. Since we are using MATSHELL, we printed max norm of
> || b || and || A*x ||, the two things that have all the physics of the
> problem. Both are coming out to be finite (no NANs). Perhaps there is a NaN
> in PCSHELL.
Thanks Matt and Barry. Since we are using MATSHELL, we printed max norm of
|| b || and || A*x ||, the two things that have all the physics of the
problem. Both are coming out to be finite (no NANs). Perhaps there is a NaN
in PCSHELL. But this is counter-intuitive because the true residual norm ||
> On May 2, 2022, at 8:12 AM, Matthew Knepley wrote:
>
> On Mon, May 2, 2022 at 12:23 AM Ramakrishnan Thirumalaisamy
> mailto:rthirumalaisam1...@sdsu.edu>> wrote:
> Thank you. I have a couple of questions. I am solving the low Mach
> Navier-Stokes system using a projection preconditioner
On Mon, May 2, 2022 at 12:23 AM Ramakrishnan Thirumalaisamy <
rthirumalaisam1...@sdsu.edu> wrote:
> Thank you. I have a couple of questions. I am solving the low Mach
> Navier-Stokes system using a projection preconditioner (pc_shell type) with
> GMRES being the outer solver and Richardson being
As given in my previous email, when ksp_pc_type is "left", the residual
norms are:
Residual norms for stokes_ solve.
0 KSP preconditioned resid norm 8.829128536017e+04 true resid norm
-nan ||r(i)||/||b|| -nan
1 KSP preconditioned resid norm 1.219313641627e+00 true resid norm
Sorry. There is a typo in my previous email. It should be ksp_pc_side.
Regards,
Rama
On Sun, May 1, 2022 at 9:23 PM Ramakrishnan Thirumalaisamy <
rthirumalaisam1...@sdsu.edu> wrote:
> Thank you. I have a couple of questions. I am solving the low Mach
> Navier-Stokes system using a projection
Thank you. I have a couple of questions. I am solving the low Mach
Navier-Stokes system using a projection preconditioner (pc_shell type) with
GMRES being the outer solver and Richardson being the Krylov
preconditioner. The solver diverges when ksp_pc_type is "right”:
Linear stokes_ solve did not
On Sun 1. May 2022 at 07:03, Amneet Bhalla wrote:
> How about using a fixed number of Richardson iterations as a Krylov
> preconditioner to a GMRES solver?
>
That is fine.
Would that lead to a linear operation?
>
Yes.
> On Sat, Apr 30, 2022 at 8:21 PM Jed Brown wrote:
>
>> In general, no.
How about using a fixed number of Richardson iterations as a Krylov
preconditioner to a GMRES solver? Would that lead to a linear operation?
On Sat, Apr 30, 2022 at 8:21 PM Jed Brown wrote:
> In general, no. A fixed number of Krylov iterations (CG, GMRES, etc.) is a
> nonlinear operation.
>
> A
In general, no. A fixed number of Krylov iterations (CG, GMRES, etc.) is a
nonlinear operation.
A fixed number of iterations of a method with a fixed polynomial, such as
Chebyshev, is a linear operation so you don't need a flexible outer method.
Ramakrishnan Thirumalaisamy writes:
> Hi,
>
>
Hi,
I have a Krylov solver with a preconditioner that is also a Krylov solver.
I know I can use "fgmres" for the outer solver but can I use gmres for the
outer solver with a fixed number of iterations in the Krylov
preconditioners?
Thanks,
Rama
13 matches
Mail list logo
