[petsc-users] zero diagonals

Barry Smith bsmith at mcs.anl.gov
Mon Apr 19 16:08:34 CDT 2010

    -pc_factor_mat_shift_type nonzero or -sub_pc_factor_shift_type  
nonzero or -mg_coarse_pc_factor_shift_type nonzero depending on where  
it is used.

    You can always run with -help and grep for shift_type to find out  
which one is needed


On Apr 19, 2010, at 4:04 PM, hxie at umn.edu wrote:

> Hi,
> I have a matrix with some zero diagonals. Now I create a new matrix  
> for preconditioner and use Matshift to avoid the zero diagonals in  
> the preconditioner matrix. It works fine. Is that possible to just  
> use the command line options? If I just want to shift the zero  
> diagonals, how can I do that? Thanks.
> Bests,
> Hui

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