[petsc-users] zero diagonals

[hxie at umn.edu]

Hi,

The Matshift will shift all the diagonals. Is there a function to shift 
only the zero diagonals?

Bests,
Hui




>Date: Mon, 19 Apr 2010 16:08:34 -0500
>From: Barry Smith <bsmith at mcs.anl.gov>
>Subject: Re: [petsc-users] zero diagonals
>To: PETSc users list <petsc-users at mcs.anl.gov>
>Message-ID: <8CCA772D-DD35-4396-9951-DF23AC833863 at mcs.anl.gov>
>Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>
>
>    -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
>
>    Barry
>
>
>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
>>
>>
>
>
>