[petsc-users] Is it possible to use -snes_ksp_ew in the framework of KSP?

[Barry Smith]

On Mar 7, 2014, at 1:21 PM, Song Gao <song.gao2 at mail.mcgill.ca> wrote:

> Hello,
> 
> We are working on a legacy codes which solves the NS equations. The codes take control of newton iterations itself and use KSP to solve the linear system. 
> 
> We modified the codes, used SNES to control the newton iteration and changed the code to matrix free fashion. But the legacy codes did a lot of other things between two newton iterations (such as output solution, update variables....). I know we could use linesearchpostcheck but it is difficulty to do that correctly.

  Please let us know what difficulties arise with the various pre and post checks, we are willing to add functionality or improve it to satisfy your needs.

   Barry

     
> Therefore, we decide to go back to the KSP framework but still use matrix free.
> 
> When using SNES, we always use the runtime option -snes_ksp_ew, we observe that for some test cases, the residual stalls without -snes_ksp_ew, but converges with-snes_ksp_ew. So I'm thinking if it is possible to use -snes_ksp_ew in KSP? Thanks in advance.
> 
>