[petsc-users] Matrix Factorization fill

[Barry Smith]

On Sep 20, 2011, at 7:02 PM, Rongliang Chen wrote:

> Hi,
> 
> I have a question about the Sparse Matrix Factorization fill. 
> Following the manual, I use the option "-info" and get the following result:
> 
> [0] MatLUFactorSymbolic_SeqAIJ(): Reallocs 0 Fill ratio:given 5 needed 5.0746e-05
> [0] MatLUFactorSymbolic_SeqAIJ(): Run with -pc_factor_fill 5.0746e-05 or use
> [0] MatLUFactorSymbolic_SeqAIJ(): PCFactorSetFill(pc,5.0746e-05);
> 
> What's the numbers mean in "Reallocs 0 Fill ratio:given 5 needed 5.0746e-05"? 
> Does the " Run with -pc_factor_fill 5.0746e-05 or use" mean that I should run my code with option " -pc_factor_fill 5.0746e-05"?

   This is printed incorrectly due to a change in our data structures, we will fix it.

> 
> But when I run my code with option "-snes_view", I get "factor fill ratio given 5, needed 3.28701". 
> So what should I give to the option "-pc_factor_fill", 3.28701 or 5.0746e-05? Thanks.

   The 3.28701

Barrty

> 
> Best,
> Rongliang