[petsc-users] MATBDIAG in > 3.1

[Parker, Andrew (UK Filton)]

Hi,

 

I've been using PETSc for a conventional full parallel implicit solver,
currently in MPIBAIJ format.  However, I'd like to understand the
performance verse memory and speed trade-offs of just having a block
diagonal system.  In this case I do not scatter to the off diagonal
blocks.  Each block is 7x7 in size and fully dense.  In my view this
should be a point implicit solution of the system.  I am looking for the
best way to solve this in PETSc, clearly because of the lack of coupling
between neighbouring cells by only having a block diagonal it's actually
a 7x7 dense linear solve, but to test my theory at present I'd prefer to
just not scatter to off diagonals, and use:

 

MATBDIAG with my current ksp solver and take it from there.  BDIAG seems
to have been removed as off 3.0:

 

http://www.mcs.anl.gov/petsc/documentation/changes/300.html

 

Can anybody help me with this, your thoughts on the above and what I
should use to solve this reduced system would be appreciated??


Cheers,

Andy


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