Symmetric matrices.

[Barry Smith]

  You need to install PETSc with the external package Spooles or MUMPS
for parallel direct solvers.

   Barry

 Click on the links from 
http://www-unix.mcs.anl.gov/petsc/petsc-as/documentation/linearsolvertable.html
for how to use them.


On Tue, 14 Nov 2006, billy at dem.uminho.pt wrote:

> 
> 
> Does the direct solver work in parallel? Because when I try it with more than 1
> processor, I get:
> 
> [0]PETSC ERROR: MatCholeskyFactorSymbolic() line 2319 in src/mat/interface/matrix.c
> [0]PETSC ERROR: No support for this operation for this object type!
> [0]PETSC ERROR: Mat type mpisbaij!
> [0]PETSC ERROR: PCSetUp_Cholesky() line 237 in
> src/ksp/pc/impls/factor/cholesky/cholesky.c
> [0]PETSC ERROR: PCSetUp() line 798 in src/ksp/pc/interface/precon.c
> [0]PETSC ERROR: KSPSetUp() line 234 in src/ksp/ksp/interface/itfunc.c
> [0]PETSC ERROR: KSPSolve() line 334 in src/ksp/ksp/interface/itfunc.c
> [1]PETSC ERROR: MatCholeskyFactorSymbolic() line 2319 in src/mat/interface/matrix.c
> [1]PETSC ERROR: No support for this operation for this object type!
> [1]PETSC ERROR: Mat type mpisbaij!
> [1]PETSC ERROR: PCSetUp_Cholesky() line 237 in
> src/ksp/pc/impls/factor/cholesky/cholesky.c
> [1]PETSC ERROR: PCSetUp() line 798 in src/ksp/pc/interface/precon.c
> [1]PETSC ERROR: KSPSetUp() line 234 in src/ksp/ksp/interface/itfunc.c
> [1]PETSC ERROR: KSPSolve() line 334 in src/ksp/ksp/interface/itfunc.c
> 
> 
> Billy.
> 
> Quoting Hong Zhang <hzhang at mcs.anl.gov>:
> 
> > 
> > > Which solvers are more appropriate for symmetric matrices?
> > 
> > Iterative solvers: ksp_type cg, pc_type icc
> > Direct solvers:    ksp_type preonly, pc_type cc
> > 
> > Non-symmetric solvers also work, but the above solvers
> > are more efficient in general.
> > 
> > You can run petsc code with various ksp/pc combinations,
> > and use the option '-log_summary' to evaluate the performance.
> > Using '-help' to see all solver options.
> > 
> > Hong
> > 
> > 
> 
> 
>