Hello,
I want to use PETSC to solve an unsymmetrical matrix. I find many linear system
solvers in PETSC. But I don't know which one is suitable for the unsymmetrical
matrix. I want to choose the best solver for my problem. Would you mind give me
some alternative solvers for the unsymmetrical mat
Hi,
I use PETSC to solve the unsymmetrical matrix which is formed by the
incompressible SPH method. Due to the scale of the problem is huge, I want to
choose the best and the most efficient solver. I have checked the time-cost of
the pre-conditioner PCGAMG together with the solvers like KSPCGS,
Hi,
I want to compare the time cost between preconditioner and unpreconditioner in
PETSc. But I didn't know how to turn off the preconditioner in Petsc. If I
choose the PCNONE, but the solution even can not converge. If I do not declare
PC at the beginning of my program, will PETSc choose a defa
after preconditioned
(e.g. PAx=Pb, and I want to get PA), is there a function in PETSc?
Thanks again!
Daye
At 2018-03-21 18:45:18, "Matthew Knepley" wrote:
On Wed, Mar 21, 2018 at 3:35 AM, 我 wrote:
Hi,
I want to compare the time cost between preconditioner and unpreconditioner in
Thank you very much for your consistent help!
At 2018-03-21 20:12:58, "Matthew Knepley" wrote:
On Wed, Mar 21, 2018 at 9:07 AM, 我 wrote:
Thanks for your reply! You mean the preconditioner must be the necessary choice
for the linear iterative method in PETSc?
No. As you sa
Hi all,
I want to analyze the preconditioned matrix. But the KSPComputeExplicitOperator
costs too much time to obtain the matrix. My origin matrix is about 3000*3000
sparse one. I noticed this function is applicable for the relative small
system. What's the matrix-size limitation for this functi
ou very much!
Daye
At 2018-03-23 07:41:26, "Matthew Knepley" wrote:
On Thu, Mar 22, 2018 at 8:29 PM, 我 wrote:
Hi all,
I want to analyze the preconditioned matrix. But the KSPComputeExplicitOperator
costs too much time to obtain the matrix. My origin matrix is about 3000*3000
spar
26:34, "Matthew Knepley" wrote:
On Sat, Mar 24, 2018 at 8:15 AM, 我 wrote:
Hi Matt,
Sorry to distribute you again. I still have trouble with
KSPComputeExplicitOperator. I reduced the matrix size to around 1000*1000. The
time-cost of this function is acceptable, but when I output the pr
you very much!
daye
At 2018-03-24 19:58:57, "Matthew Knepley" wrote:
On Sat, Mar 24, 2018 at 8:56 AM, 我 wrote:
Hi Matt,
I have tested my code with a really small matrix(10*10) just now and the
preconditioned matrix is obtained. But for my case, the output is still equal
Hello,
I want to change the row order of a sparse matrix. Are there any build-in
functions and suggestions?
Thank you very much!
Daye
need to do anything.
>
> The ordering of matrix rows corresponds to the ordering of the vectors;
> almost always one partitions and orders the vectors based on the mesh that
> underlies the problem and there is no reason to reorder once the layout is
> initially determined.
>
>
Hello all,
I use the function MatCreateMPIAIJWithArrays to construct my matrix. But the
number of local rows m and local columns n may change during the timestep
advancing. When the local size changes, the error like "Petsc error: cannot
chang local size of Amat after use old sizes 10 10 new si
"Matthew Knepley" wrote:
On Fri, May 11, 2018 at 4:23 AM, 我 wrote:
Hello all,
I use the function MatCreateMPIAIJWithArrays to construct my matrix. But the
number of local rows m and local columns n may change during the timestep
advancing. When the local size changes, the error
Hello all,
I set PCGAMG and KSPGRMES to solve the matrix which is formed by a particle
method such as SPH. But when there is always a PETSC ERROR:
[2]PETSC ERROR: - Error Message
--
[2]PETSC ERROR: Petsc has generate
an try to make it symmetric.
>
>
>> [2]PETSC ERROR: Have un-symmetric graph (apparently). Use
>> '-(null)pc_gamg_sym_graph true' to symetrize the graph or
>> '-(null)pc_gamg_threshold -1' if the matrix is structurally symmetric.
>
>
>
>> On Jul 9,
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