[petsc-users] fill factor in factorization SLEPC

[Hong Zhang]

You may try -st_redundant_pc_factor_fill <fill>.
Here is how I found the option using
slepc-3.4.4/src/eps/examples/tutorials/ex13.c:
1)
./ex13 -info | |grep fill
[0] MatLUFactorSymbolic_SeqAIJ(): Run with -pc_factor_fill 2.95217 or use

2)
./ex13 -help |grep fill
  -st_redundant_pc_factor_fill <5>: Expected non-zeros in factored
matrix (PCFactorSetFill)
  -st_redundant_pc_factor_reuse_fill: <FALSE> Use fill from previous
factorization (PCFactorSetReuseFill)

i.e., the default fill=5, sufficient for this case. There is no need
to set as 2.95217. If you want to, do
./ex13 -st_redundant_pc_factor_fill 2.95217 -info
...
[0] MatLUFactorSymbolic_SeqAIJ(): Reallocs 0 Fill ratio:given 4 needed 2.95217
[0] MatLUFactorSymbolic_SeqAIJ(): Run with -pc_factor_fill 2.95217 or use
[0] MatLUFactorSymbolic_SeqAIJ(): PCFactorSetFill(pc,2.95217);

As you see, Reallocs 0, good performance.

Hong

On Thu, Jul 3, 2014 at 9:45 PM, jifeng zhao
<jifengzhao2015 at u.northwestern.edu> wrote:
> Hi all,
>
> I am using SLEPC to solve an eigenvalue problem.
>
> I tried to add -info at run time. And I get instruction:
>
> MatLUFactorSymbolic_SeqAIJ(): Run with -pc_factor_fill 3.87526 or use
> MatLUFactorSymbolic_SeqAIJ(): PCFactorSetFill(pc,3.87526);
> MatLUFactorSymbolic_SeqAIJ(): for best performance.
>
> However, when I tried to add -st_pc_factor_fill 3.87526 at run time. It is
> not recognized at all!
>
> WARNING! There are options you set that were not used!
> WARNING! could be spelling mistake, etc!
> Option left: name:-st_pc_factor_fill value: 3.87526
>
> Same things happened if I tried pc_factor_fill 3.87526
>
> Does anybody know how to change the fill of factorization for SLEPC?
>
> Thanks,
> Jifeng Zhao
>
> --
> Jifeng Zhao
> PhD candidate at Northwestern University, US
> Theoretical and Applied Mechanics Program