Using ML via PETSc

[Hong Zhang]

Stephen,

>
> > I am looking to have a go at using Sandia National Laboratory's ML
> > preconditioning package via PETSc. I have looked in your python script
> > for ML and the download link refers to v4.0. However, looking at your
> > ftp download site I can see that v5.0 is included. Can you tell me if it
> > is to safe to use the v5.0 version with PETSc v2.3.2 or should I use
> > v4.0.
>
> You might just need the following patch to get ML5.0 working with
> petsc-2.3.2
>
> http://petsc.cs.iit.edu/petsc/petsc-dev/diff/882b30353a21/src/ksp/pc/impls/ml/ml.c
>

Petsc-dev is compatible with ML5.0.
petsc-2.3.2 is interfaced with ML4.0
config petsc with '--download-ml=1' gives you
compatible ML.

> >
> > Also, can you tell me if there are any examples of using ML via PETSc.
>
> Any ksp example with '-pc_type ml' shold work...

Not necessarily.
ML requires input of fine-grid matrix, then it determines nlevels;
while petsc let user define nlevels.
See
petsc-2.3.2/src/ksp/ksp/examples/tests/ex26.c
(run with -pc_type ml -ksp_view)
or
petsc-dev/src/ksp/ksp/examples/tests/ex29.c

Hong
>