Dear developers,
To avoid zero pivot error in IC/ILU preconditioners, I plan to permute matrix
before solving the linear system. I referred example
ex10(https://petsc.org/main/src/ksp/ksp/tutorials/ex10.c.html) and
ex18(https://petsc.org/main/src/ksp/ksp/tutorials/ex18.c.html), and was
struct the RBMs yourself and set them with
https://petsc.org/release/docs/manualpages/Mat/MatNullSpaceCreateRigidBody.html
There is some discussion here:
https://www2.eecs.berkeley.edu/Pubs/TechRpts/2000/CSD-00-1103.pdf
Mark
On Tue, Sep 27, 2022 at 6:20 AM 晓峰 何
mailto:tlan...@hotmail.com>>
Hello,
A00 comes from shell structures and discretized by FEM.
Thanks,
Xiaofeng
On Sep 27, 2022, at 17:48, Mark Adams mailto:mfad...@lbl.gov>>
wrote:
what equations and discetizations are in A00?
On Tue, Sep 27, 2022 at 1:45 AM 晓峰 何
mailto:tlan...@hotmail.com>> wrote:
Hi
e best preconditioner to use for the A11 (the Schur complement
block), once you have a good preconditioner for the A11 block you would then go
back and determine a good preconditioner for the A00 block.
On Sep 26, 2022, at 10:08 AM, 晓峰 何
mailto:tlan...@hotmail.com>> wrote:
Hello Jed,
The
ssible elasticity. There is an example in PETSc
for Stokes I believe.
Thanks,
Matt
On Mon, Sep 26, 2022 at 5:20 AM 晓峰 何
mailto:tlan...@hotmail.com>> wrote:
Are there other approaches to solve this kind of systems in PETSc except for
field-split methods?
Thanks,
Xiaofeng
On Sep 26, 20
Hello Jed,
The saddle point is due to Lagrange multipliers, thus the size of A11 is much
smaller than A00.
Best Regards,
Xiaofeng
On Sep 26, 2022, at 21:03, Jed Brown
mailto:j...@jedbrown.org>> wrote:
Lagrange multipliers
ag(A00)^{-1} works poorly because the resulting operator behaves like
a Laplacian rather than like a mass matrix.
晓峰 何 mailto:tlan...@hotmail.com>> writes:
If assigned a preconditioner to A11 with this cmd options:
-fieldsplit_0_ksp_type gmres -fieldsplit_0_pc_type ilu -fieldsplit_1_ksp
quot;
How could I specify a preconditioner for A11?
BR,
Xiaofeng
On Sep 26, 2022, at 11:02, 晓峰 何
mailto:tlan...@hotmail.com>> wrote:
-fieldsplit_0_ksp_type gmres -fieldsplit_0_pc_type ilu -fieldsplit_1_ksp_type
gmres -fieldsplit_1_pc_type none
Hi all,
I have a linear system formed from structural mechanics, and there exists zero
in the diagonal entries:
A = (A00 A01
A10 A11), where A00 has inverse and the diagonal entries in A11 are all
zero.
The GMRES method with ILU preconditioner in PETSc was carried out to solve this
