[petsc-users] ML options

[Sanjay Govindjee]

I am adding ML as an option to our FEA code and was looking for a bit of 
guidance on
options.  Generally we solve 1,2, and 3D solids problems (nonlinear 
elasticity) but
we also treat shells, thermal, problems, coupled problems, etc. etc.

My basic run line looks like:

-@${MPIEXEC} -n $(NPROC) $(MY_PROGRAM) -ksp_type cg -ksp_monitor 
-pc_type ml  -log_summary  -ksp_view  -options_left

but this does not work very well at all with 3D elasticity for example 
-- in fact it fails to converge after 10K iterations on a rather
modest problem.  However following ex26 in the ksp tutorials I also tried:

-@${MPIEXEC} -n $(NPROC) $(FEAPRUN) -ksp_type cg -ksp_monitor -pc_type 
ml -mat_no_inode -log_summary  -ksp_view  -options_left

And this worked very very much better -- converged in about 10 
iterations.  What exactly is -mat_no_inode doing for me? and are there 
other 'important' options
that I should be aware of when using ML.

-sanjay